A Systematic Review of Exercise Training in Patients With Cardiac Implantable Devices : Journal of Cardiopulmonary Rehabilitation and Prevention

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Invited Review

A Systematic Review of Exercise Training in Patients With Cardiac Implantable Devices

Alswyan, Afnan Hamad RN, MSN, CCRN; Liberato, Ana Carolina Sauer RN, MS; Dougherty, Cynthia M. ARNP, PhD, FAAN

Author Information
Journal of Cardiopulmonary Rehabilitation and Prevention 38(2):p 70-84, March 2018. | DOI: 10.1097/HCR.0000000000000289

Exercise training has been shown to be beneficial in improving health status, survival, and quality of life (QoL) in those with heart disease.1–3 However, patients with heart disease who have cardiac implantable devices (CIDs), such as implantable cardioverter defibrillators (ICDs), cardiac resynchronization pacemakers or defibrillators (CRT-P or CDT-D, respectively), or ventricular assist devices (VADs), have additional specific issues when performing exercise. The ICD is used to treat cardiac arrest by delivering ICD shocks to terminate lethal cardiac arrhythmias.4,5 It is common after getting an ICD for patients to be afraid to exercise because of fear of receiving an ICD shock with elevated heart rates (HRs) associated with exercise.6 As well, clinicians are not often confident in prescribing exercise in relation to intensity, duration, or frequency to improve aerobic capacity while not causing an ICD shock.7 Cardiac resynchronization therapy (CRT) has been shown to reduce heart failure (HF) symptoms, hospitalizations, and mortality, while increasing exercise capacity, cardiac performance, and QoL in HF with reduced ejection fraction.5,8,9 However, in one-third of CRT recipients, there is lack of improvement of symptoms.10 Some possible reasons include insufficient evidence of mechanical dyssynchrony before CRT implantation, lack of myocardial contractile reserve, severe mitral regurgitation, suboptimal left ventricular lead position, and inappropriate device programming.11,12 In patients with CRT, exercise can partially restore endothelial function, improve skeletal muscle abnormalities, and reverse ventricular remodeling.13,14 The implantation of a VAD (LVAD, RVAD, BiVAD) in advanced HF is used as destination therapy or as bridge to heart transplantation.15 Patients with a VAD are often functionally debilitated with low exercise tolerance at the time of implant.16,17 During exercise training, the VAD needs to be carefully managed and titrated by trained personnel in order to build patient endurance while maintaining safety.18,19 Maximal exercise capacity will remain reduced even after exercise interventions, due to the fixed pump speed, which provides insufficient support with moderate-high levels of physical exertion.20

There are few published systematic reviews on exercise training in patients with CIDs: 2 for ICD,19,21 no reviews specifically for CRT but many reviews in the HF population,22–26 and 1 for patients with a VAD.20 The previous reviews for the ICD have shown that exercise training is safe, improves aerobic capacity, and is not associated with an increased risk of ICD shock or other adverse events.19–21 However, there are equivocal findings for the effect of exercise training on anxiety, depression, and QoL.21 The systematic review for VAD recipients concluded that exercise training improves aerobic capacity, but exercise capacity remains reduced after VAD implantation.20

The purpose of this systematic review is to outline the benefits of exercise interventions in those who have an ICD, CRT, and/or VAD device. Given the small number of existing reviews regarding CIDs, the key objectives of this systematic review are to (1) identify exercise-based intervention studies in patients with CIDs and (2) assess evidence for the efficacy of exercise-based interventions alone or in combination with psychoeducational components.



This systematic review contains all available studies reporting a clinical outcome in CID recipients who underwent some form of exercise-based intervention. A protocol meeting the “A Measurement Tool to Assess Systematic Reviews” (AMSTAR) tool criteria27–29 was developed and implemented. The AMSTAR is an assessment tool with good face and construct validity to ensure the reliability of the findings and ability to apply the conclusions drawn with a high degree of confidence.

Exercise training was defined as an intervention that must have included an aerobic or resistance exercise component for adults treated with a CID. The interventions could be implemented in a supervised or unsupervised program conducted in an outpatient, community, or home setting that included any kind of exercise training regimen. The intervention must have involved a physical exercise component that focused on increasing exercise capacity and may also have included a psychoeducational component to improve mental health or self-management skills. The exercise intervention must have been implemented in the outpatient setting but could have been initiated in the hospital and continued after hospital discharge. There were no restrictions in the length, intensity, or content of the training program, minimum length of follow-up, or collection of pre-specified outcomes. All studies that were found in the literature were included regardless of design or study quality.

The inclusion criteria were (1) published articles that focused on the effect of exercise training in patients with a CID (ICD, pacemaker, and VAD); (2) involvement of human subjects; (3) article published in English in a peer-reviewed journal; and (4) patients were adults aged 18 years and older. The articles were excluded if they were (1) editorials, commentaries, conference abstracts, opinion pieces, protocol papers, or review papers; (2) focused solely on exercise testing; or (3) examined exercise interventions performed only in the inpatient setting.


A systematic search of the databases PubMed, EMBASE, CINAHL Plus, Web of Science, Cochrane, and PEDro was conducted for each of the 3 CIDs: (1) ICD (keyword: implantable cardioverter defibrillator); (2) VAD (keywords: ventricular assist device, LVAD, VAD); and (3) CRT/resynchronization pacemaker (keywords: pacemaker, cardiac resynchronization therapy). All 3 searches included a combination of the search terms: exercise, aerobic exercise, rehabilitation, resistance exercise, cardiopulmonary rehabilitation, exercise therapy.

Search parameters were adapted to database requirements and combined and exploded MeSH terms and text words related to exercise and different terms related to each implantable device (ICD, LVAD, and CRT). Details of these adapted searches may be requested from the authors. The bibliographies of all included studies and review articles were screened for further references. Two reviewers independently screened each citation for potential relevance against eligibility criteria. Databases were searched from their inception to September 1, 2016. No conference abstracts, conference titles, editorial pages, newspapers, or center-based literature was included in the search.


Study Selection

The titles of publications identified in the searches were independently screened by 2 authors and coded for eligibility for the review (eligible, potentially eligible/unclear, not eligible). Search results were imported into a spreadsheet and duplicates were removed. After exclusions were completed on the basis of the title, abstracts were reviewed. Articles meeting the inclusion criteria were identified. The full papers were obtained for all studies meeting the review criteria. Multiple publications from the same study were extracted so that each study sample was represented only once. A flow diagram (Figure) illustrates the process of inclusion and exclusion of all studies.

Flowchart for the results of the literature search. Abbreviations: CRT, cardiac resynchronization therapy; ICD, implantable cardioverter defibrillator; VAD, ventricular assist device. aThere were 27 articles included, however multiple publications from the same study dataset were represented only once.

Search Outcomes

The initial search of all databases yielded 3991 articles for all CIDs (ICD: 1015, pacemaker: 1630, and VAD: 1346) that were screened for relevance. The titles of 421 studies (ICD: 159, 114: pacemaker; and VAD: 148) was selected to be reviewed with accompanying abstracts. After removal of duplicates, the remaining 196 (ICD: 51; pacemaker: 54; VAD: 91) articles were screened for eligibility criteria on the basis of abstracts. Subsequently, 47 full-text articles (ICD: 29; CRT 6; VAD: 12) were retrieved and reviewed for suitability for this review. Of these, 24 articles (ICD: 141,6,30–44, CRT: 43,13,45,46, and VAD: 617,47–51) were eligible for this review and were appraised for quality. Reference lists of appropriate studies were hand-searched to identify further studies for potential inclusion. This method identified 5 additional articles that were screened for eligibility. The included studies from the electronic database literature search are summarized in Tables 1 to 3. There was no blinding to study author, institution, or journal that occurred during the study screening process.

Table 1 - Studies Included With ICD Implantation
Study Design, n Sample
Age, Mean ± SD
Male Sex, n (%)
EF%, Mean ± SD
Intervention Outcomes Results
Exercise Versus Control
Mean Change ± SD
Fitchet et al (2003)30
RCT crossover;
n = 16
Sample: ICD for secondary prevention
Male sex: 14 (88%)
Age: 58 ± 10 y
EF%: 38 ± 17
Group 1: 50%
Group 2: 12.5%
EX: CR with tailored aerobic exercise (1.5 hr/2×/wk at 60%-75% of HR) × 12 wk
Education/cognitive behavioral intervention (30 min/wk)
Supplementary exercise at home/community
Psychological support/intervention (n = 8)
C: 12 wk usual care (n = 8)
12 wk post-program:
Exercise capacity
Exercise time, min
The Norwegian HADS-A
The Norwegian HADS-D
Exercise capacity (EX vs C)
↑Exercise time, 1.6 ± 2.6, P = NR
↓HADS-A: 5.2 ± 1.1, P = NR
↓HADS-D: 2.8 ± 0.3, P = NR
Adverse events
ICD shocks during exercise: 0
During the study period: 2 in 2 patients
Frizelle et al (2004)31
RCT crossover;
n = 22
Sample: ICD for uncontrolled ventricular arrhythmia (100%)
Male sex: NR
Age: 62 ± 7 y
EX: 60 ± 10; C: 63 ± 5
Group 1: (immediate participation): 0%
Group 2: (waiting): 0%
EX: Hospital-based cognitive behavioral CR program: 2 hr/wk × 12 wk + home exercise
Educational and discussion sessions about ICD concerns
Muscular relaxation; Breathing exercises, Setting and pacing activity, Support group (n = 12)
C: Routine care wait × 12 wk, then 12 wk of CR (n = 10)
12 wk:
Shuttle walk test
Level of difficulty
Total distance walked, m
Borg rating of exertion
MacNew QOL after MI (MacNew QLMI)
Shuttle walk test
↑Level 1.4 ± 0.6, P = .05
↑Distance 85.5 ± 24.1, P = .01
↑Borg rating, 5.6 ± 1.9, P = NS
↓HADS-A 1.1 ± 1.2, P = .01
↓HADS-D 1.6±1.2, P = .001
MacNew (emotional)
↑0.4 ± 0.7, P = .05
MacNew (Physical)
↑0.7 ± 0.7, P = .008
↑9.6 ± 6.8, P =.05
Adverse events: 1 death not cardiac related
Vanhees et al (2004)32
ICD, n = 92;
Control, n = 473
Sample: Consecutive patients with ICDs from 2 centers
Male sex: EX: 79 (86%); C: 428 (90%)
Age: EX: 57 ± 12 y; C: 56 ± 8 y
EF%: <40: EX: 23; C: 41
Dropouts: 14 (13.2%)
EX (cases): ICD patients who participated in a supervised exercise rehabilitation program (90 min/3×/wk for 12 wk; 50%-80% of maximal HR; n = 92), plus outdoor activities
C: Cardiac patients without an ICD who had a CPET and completed CR program × 12 wk (n = 473)
All patients: 4-5 education sessions related to heart disease, psychology, and diet.
12 wk:
Exercise capacity
Peak o 2, mL/kg/min
Peak oxygen pulse, mL/beat
Maximum HR, beats/min
Arrhythmias during EX testing
Adverse events
ICD shocks
Exercise capacity (EX vs C)
↑Peak o 2 7.5 ± 2.1, P < .001
↑O2 pulse, 2.1 ± 0.9, P < .001
↑Max HR = NS
Arrhythmias EX testing
VT during testing without ICD shock: 1
Adverse events
VT during training: 1
ICD shock: 1
Inappropriate ICD shocks: 1
Appropriate ICD shocks outside of exercise training: 6
Davids et al (2005)33
Retrospective telephone survey comparative study;
n = 82
Sample: Coronary artery disease and ICD between 1997 and 2001. No patients underwent exercise interventions conducted by the study.
Male sex: 71 (86.6%)
Age: 61 ± 1 y; EX: 60 ± 2 y; C: 62 ± 1 y
EF%: EX: 37 ± 2; C: 35 ± 2
Dropouts: NR
EX: Any outpatient CR program (n = 28)
C: No CR (n = 54)
Telephone survey:
Exercise capacity (self-report)
METs (per wk)
Frequency of regular exercise (times/wk) median #
Exercise >3 times/wk, n (%)
Decrease in exercise after ICD implantation (times/wk)
Adverse events
(EHR) ICD shock n (%)
Any shock
Appropriate shocks
Inappropriate shocks
Shocks during exercise
Appropriate shocks during exercise
Inappropriate shocks during exercise
Exercise capacity (EX vs C)
↑METs: 1.8, P < .02
↑Frequency of regular exercise = 1.0, P = .11
↑Exercise >3 times/wk, 25%; P = .30
Decrease in exercise after ICD implantation, 16%, P = .15
Adverse events (EX vs C): n (%)
↓Any shocks, 20 (25%), P < .03
↓Appropriate shocks, 17 (26%), P = .03
↓Inappropriate shocks, 12%, P = .17
Shocks during exercise, 0, P = .02
Appropriate shocks during exercise, 0, P = .02
Inappropriate shocks during exercise, 0, P = .10
Belardinelli et al (2006)1
Prospective RCT;
n = 52
Sample: NYHA FC II heart failure, ischemic cardiomyopathy, primary and secondary prevention
Male sex: 52 (100%)
Age: EX: 55 ± 14 y; C: 53 ± 15 y
EF%: EX: 30 ± 7; C: 34 ± 8
Dropouts: NR
EX: Aerobic exercise (1 hr, 3×/wk at 60% peak o 2 8 wk)
(n = 30; ICD n = 15; CRT-D n = 15)
C: Avoid physical training (n = 22; ICD n = 12; CRT-D n = 10)
8 wk:
Exercise capacity
Peak o 2, mL/kg/min
Adverse events
ICD shocks, death
Exercise capacity
↑Peak o 2, 2.8 ± 0.5, P < .001
↑AT, 3.2 ± 0, P < .001
↑MLHFQ, 8.0, P = NS
Adverse events
ICD shocks, EX = 0, C = 8
No deaths
No complex ventricular arrhythmias during training sessions and follow-up in EX group.
Dougherty et al (2008)34
Single group pre-post;
n = 10
Sample: Sudden cardiac arrest survivors (n = 4) or sustained ventricular arrhythmia (n = 6) with ICD implant in previous 6 mo
Male sex: 9 (90%)
Age: 55 ± 9 y
EF%: 39 ± 20
Dropouts: 0
EX: Supervised outpatient aerobic exercise (3 hr/wk + home walking 2h/wk × 8 wk: at 60%-80% of maxHR.) Remaining 4 mo: walk for 30 min on all or most days 8 wk:
Exercise capacity
Peak o 2, mL/kg/min
Exercise time, min:sec
Exercise capacity (pre vs post)
↑Peak o 2, 0.4 ± 10.5, P = .78
↑Exercise time, 1:05 ± 00:38, P = .04
↑METs, 0.5 ± 2.7, P = .33
↑SF-12 PCS 2.9 ± 10, P = .19
↑SF-12 MCS 3.7 ± 9.5, P = .48
↓STAI 3.3 ± 10.2, P = .06
↓CES-D 1.8 ± 3.1, P = .69
Adverse events:
No sustained arrhythmias during exercise testing or exercise interventions.
No ICD shocks.
Fan et al (2009)35
Retrospective case-control chart review;
n = 84
Sample: ICD patient and controls who participated in CR between 1992 and 2005 at single center
Male sex: EX: 32 (76%); C: 33 (79%)
Age: EX: 61 ± 12 y; C: 61 ± 14 y
EF%: EX: 32 ± 15; C: 36 ± 13
Dropouts: Dropout secondary to cardiac reason: EX: 9%; C: 12%
EX (cases): Supervised exercise training in CR (intensity of 50%-85% of HRR using telemetry monitoring for 30-60 min/3 times/wk using various upper- and lower-body training modalities); n = 42
C: Matched controls without ICD who participated in CR as defined previously; match based on EF, age, sex; n = 42
End of program:
Exercise capacity
Adverse event
ICD shocks
Need for CPR
Exercise capacity
↑MET = 7%, P = NS
Hospitalizations, EX: 4; C: 1
Death: 0
Adverse events
ICD shocks during exercise, EX: 1
ICD shocks outside of exercise, EX: 0
CPR: 0
Piccini et al (2013)36
Prospective RCT;
Total n = 2331, with an ICD
n = 1053
Sample: Outpatients with HF and EF <35%, ICD or biventricular ICD
Ischemic cardiomyopathy 61%
ICD at baseline 1053 (45% of total)
Female sex: EX: 113 (21%); C: 109 (21%)
Male sex: EX: 433 (79%); C: 398 (79%)
Age (median): EX: 61 y; C: 60 y
EF % (median): EX: 24; C: 24
Dropouts: EX: 35%
EX: Supervised aerobic exercise training (36 sessions 3×/wk for 3 mo at 60%-70% target HR), followed by home-based exercise training 5×/wk × 2-4y (n = 546)
C: Usual care with no restrictions in activity (n = 507)
3 mo:
Exercise capacity
Peak o 2, mL/kg/min, change from baseline EX (mean, SE)
With ICD at baseline and without an ICD at baseline
Adverse events (2.2-y follow-up)
Composite endpoint of IDC shock/death
Exercise capacity (EX vs C)
↑Peak o 2
EX With ICD = 0.7 ± 0.1, P = NS
C With ICD = 0.1 ± 0.1, P = NS
Without an ICD, 0.9 ± 0.1, P = NS
Adverse events
ICD shock or death
EX: 32%; C: 35%, P = NS
Smialek et al (2013)37
n = 45
Sample: 1st time ICD implantation at 6 wk after ICD implantation
Male sex: 28 (62%)
Age: 62 y
EF%: 30 ± 13
Dropouts: NR
EX: Comprehensive CR inpatient and outpatient phases.
Inpatient phase (2 wk)
1. Interval endurance training (repeated sequences of short exercise and a resting period)
2. Resistance training (15-20 min/1-2 sessions/wk)
3. Respiratory muscle exercise
Outpatient phase II (12 wk) Aerobic interval endurance training including or alternating with resistance training (20-50 min/5×/wk for 12 wk)
12 wk:
Exercise capacity
Peak o 2, mL/kg/min
Polish version of SF-36 scores (higher scores = lower QOL);
Physical dimension
Adverse events
Death or complication during exercise testing or training
Arrhythmias and safety
ICD shocks
Nonsustained VT without device intervention
Inappropriate ICD shocks
Appropriate ICD shock
Exercise capacity (Pre vs post)
↑Peak o 2: 2.9 ± 1.1, P = .007
↓BDI, 1.9 ± 1.5, P = .02
↑Physical dimension: significant Improvement, data not provided
Adverse events
Death: 0
Complication during testing or training: 0
Arrhythmias and safety
Nonsustained VT without ICD shock: 7
Inappropriate ICD shock: 1 (2.2%)
Appropriate ICD shock: 2 (4.4%)
ICD shock during exercise: 0
Toise et al (2014)38
Prospective RCT;
n = 55
Sample: ICD implant in prior 6 wk
Male sex: EX: 18 (69%); C: 18 (90%)
Age: 66 ± 13 y
EF %: EX: 33 ± 15; C: 35 ± 15
EX: 16.1%; C: 16.7%
EX: Gentle adapted yoga program (consistent movements with daily life activity, breathing techniques, adapted physical postures, relaxation, and meditation) for ICD patients (80 min/wk sessions for 8 wk) + Standard medical care + 6-mo follow-up post-intervention
(n = 31)
C: Standard medical care with cardiac nurse follow-up for nonroutine device concerns + 5 monthly calls from the cardiac nurse (n = 24)
2 mo:
Psychological (change from baseline)
Device therapies = 6 mo follow-up
CD shocks
Psychological (EX vs C)
↓CES-D, 4.3 ± 6.7, P = NS
↓FSAS, 1.8 ± 2.1, P = .0001
DT: EX group had fewer expected ICD events over 8 mo; results not presented for the events/group
Berg et al (2015)39
Berg et al (2015)40
Christensen et al (2015)44
Prospective RCT;
n = 196
Sample: 1st time ICD implantation, exercise start after 3 mo of implantation
VF arrest prior to ICD 20% each group
Male sex: EX: 79 (80%); C: 76 (78%)
Age: EX: 58 ± 13 y; C: 57 ± 13 y
EF %: EX: 32 ± 17; C: 33 ± 18
Dropouts at 3 mo:
EX: 13.1%; C: 18.6%
EX: Aerobic and resistance training (aerobic exercise + resistance 1 h×2×/wk at 50-80% of estimated HR × 12 wk)
Psychoeducational: 1×/mo for 6 mo and then every 2 mo for 1 y, Total sessions = 9 (n = 99)
C (n = 97): 2-hr group session on the ICD × 1
3 mo:
Exercise capacity
Peak o 2, mL/kg/min
SF-36: General health (GH);
Mental component score (MCS)
ICD therapy
ICD shock
Exercise capacity
↑Peako 2, 0.1 ± 7.8, P = NS
↑SF-36 GH 1.6 ± 20, P = NS
↑SF-36 MCS 0.2 ± 9.5, P = NS
ICD therapy
↓ATP 5.4 ± 5.5, P = .29
ICD shock 0.1 ± 1.7, P = .90
Mortality 19% vs 12%, P = .19
Dougherty et al (2015)6
Prospective RCT;
n = 160
Sample: ICD recipients 3.1 y after implant
Male sex: 124 (77.5%)
Age: EX: 56 ± 12 y; C: 54 ± 12 y
EF%: 40.6 ± 15.7
8 wk: EX: 6.6%; C: 8.3%
24 wk: EX: 10.5%; C: 11.9%
EX: Home walking
Phase 1: 1 hr/d × 5 d/wk for 8 wk at 60%-80% of HRR
Phase 2: Home walking 30 min/d × 5d/wk for 16 wk at 80% of HRR (n = 84)
C: No exercise directives; 5 monthly phone calls (n = 76)
8 wk:
Exercise capacity
Peak o 2, mL/kg/min
Exercise time, min:sec
o 2 at AT
Exercise time at AT, min:sec
Exercise capacity (EX vs C)
↑Peak o 2, 2.8 ± 0.4, P = .002
↑Exercise time, 2.7 ± 17, P = .001
o 2 at AT, 2.5 ± 1, P = .009
↑Time at AT, 2:5 ± 1:1, P = .001
METs, 0.8 ± 0.07, P = .005
Adverse events (over 24 wk)
ICD shocks
Associated with exercise: 0
Associated with exercise: EX: 0, C:0
Isaksen et al (2015)42
Isaksen et al (2016)43
Prospective, controlled, nonrandomized;
n = 38
Sample: Ischemic HF primary and secondary prevention, first-time ICD or CRT-D
Male sex: EX: 21(88); C: 11 (100)
Age: EX: 65 ± 9 y, C: 69 ± 9 y
EF %: EX: 37 ± 11; C: 30 ± 8
Dropout rate: EX: 9.2%; C: 8.0%
EX: Outpatient cardiac rehabilitation (60 min/3×/wk for 12 wk; 60%-70% of maxHR, Borg ratings 11-13 and four 4-min intervals at 85% of maxHR, Borg ratings 15-17 (n = 26)
C: controls were those unable to attend exercise sessions (n = 12)
12 wk:
Exercise capacity
Peak o 2, mL/kg/min
Norwegian SF-36: MCS and PCS
Norwegian HADS-A and HADS-D
Arrhythmias and safety
ICD shocks
Adverse events:
ICD therapies
All-cause hospitalization rates
Exercise capacity (EX vs C)
↑Peak o 2, 2.2 ± 2.6, P < .05
↑SF-36 MCS, 4.1, P = NR
↑SF-36 PCS, 5.8, P = NR
↓HADS-A, 2.3, P = NR
Depression (EX vs C)
↓HADS-D, 1.8, P < .05
Arrhythmias and safety
ATP/NSVT: 1/group, P = NR
Shock = 0, P = NS
Adverse events
ICD therapies
During exercise: 0
During follow-up = NS
All-cause hospitalizations = NS
Lau et al (2016)44
Single sample pre-post;
n = 301
Sample: Initial ICD implant, 1 mo after ICD for primary or secondary prevention
Male sex: 222 (73.8%)
Age: 64 ± 12 y
EF ≤35%: 206 (68.4%); >35%: 95 (31.6%)
Dropouts: Pre-/post-9.6%
EX: 12-wk telephone-based home walking self-efficacy intervention (30 min/d/×12 wk at 60%-80% of age-adjusted HR)
Individualized program at a level that they were capable of before ICD implant.
Nurse weekly call to monitor exercise tolerance and safety
3 mo:
ICD shocks
ATP therapies
Total hospitalizations, n (%)
Daily physical activity (StepWatch) in steps/d
Safety (pre vs post)
ICD shocks: 19 (6.3%)
ICD shocks associated with exercise 2 (7.1%)
ATP therapies
Total ATP events: 72
ATP associated with walking: 2 (2.8%)
Total individuals: 40 (13.3%)
Total hospitalizations: 54
Hospitalizations associated with ICD shock or ATP: 5 (9.2%)
Hospitalizations associated with ICD shock and walking: 0 (0%)
Efficacy (pre-post)
†Total steps/d: 806.7 ± 351.8, P < .001
Abbreviations: AT, anaerobic threshold; ATP, anti-tachycardia pacing; BDI, Beck Depression Inventory; C, control; CES-D, Centers for Disease Epidemiology Depression Scale; CPET, cardiopulmonary exercise test; CPR, cardiopulmonary resuscitation; CR, cardiac rehabilitation; CRT-D, cardiac resynchronization-defibrillator; EF, ejection fraction; EHR, electronic health record; EX, exercise; FSAS, Florida Shock Anxiety Scale; GH, general health; HADS-A, Hospital Anxiety and Depression Scale-Anxiety; HADS-D, Hospital Anxiety and Depression Scale-Depression; HR, heart rate; HRR, heart rate reserve; ICD, implantable cardioverter defibrillator; MCS, mental composite score; METs, metabolic equivalents; MI, myocardial infarction; MLHFQ, Minnesota Living with Heart Failure Questionnaire; NR, not reported; NS, not significant; NSVT, nonsustained ventricular tachycardia; NYHA FC, New York Heart Association Functional Classification; QOL, quality of life; RCT, randomized controlled trial; SF-12 MCS, Short Form-12 item Mental Composite Summary; SF-12 PCS, Short Form-12 item Physical Composite Summary; STAI, State-Trait Anxiety Inventory; o2, oxygen uptake; VT, ventricular tachycardia.

Table 2 - Studies Included With CRT Implantation
Study Design, N Sample Age, Mean ± SD Male Sex, n (%) EF%, Mean ± SD Dropouts Intervention Outcomes Results Exercise Versus Control Mean Change + SD
Conraads et al (2007)13
Prospective RCT
n = 36
Sample: LV systolic dysfunction, LBBB, CRT, EF <35%, 1 mo after CRT
Sex: (M/F)
CRT group: CRT+: 3/5; CRT−: 5/4
C group:
HF+: 7/2; HF−: 7/3
CRT group:
CRT+: 57 ± 2 y; CRT− : 61 ± 4 y
C group:
HF+: 65 ± 3 y; HF−: 64 ± 4 y
EF %:
CRT group: CRT+: 27 ± 5; CRT−: 28 ± 5
C group: HF+: 28 ± 3; HF−: 26 ± 2
Dropouts: NR
EX: Supervised ambulatory endurance exercise program (1 hr × 3×/wk for 4 mo at HR = 90% of the ventilatory threshold (n = 17)
CRT+: Standard pharmacological therapy plus 4-mo endurance exercise training program with CRT (n = 8)
HF+: Standard pharmacological treatment plus 4 mo endurance exercise training: no CRT (n = 9)
Control: (n = 19)
Standard pharmacological therapy with CRT (n = 9)
Standard pharmacological treatment, no CRT (n = 10)
5 mo:
Exercise capacity
Peak o 2 (mL/kg/min)
Exercise capacity: (CRT+vs CRT−)
↑Peak o 2: 5.5 ± 1.0
↑Wpeak: 26 + 11, P = .005
↑MLHF: 6 ± 6.5, P = NS
Adverse events: No lead dislodgement; normal LV threshold
Patwala et al (2009)45
Prospective RCT
n = 50
Sample: NYHA FC III-IV, received CRT, LVEF% <35, 3 mo after CRT
Male sex: 46 (92%)
Age: 64 ± NR
EF %: 24
Dropouts: NR
EX: Physician-supervised exercise training (30 min/3visit/wk at 80% of peak heart rate achieved at the 3-mo test for the first 4 wk, 85% for the next 4 wk and 90% for the final 4 wk), n = 25
C: No specific advice on exercise training and no supervised training, n = 25
6 mo:
Exercise capacity
Peak o 2, mL/kg/min
%peak o 2 at AT
Exercise capacity (EX vs C)
↑Peak o 2: 2.0 ± 3.9, P = .02
↑%Peak o 2 at AT: 7.9 ± 10.5, P = NS
↓MLHFQ: −3.3 ± 19.1, P = .02
Adverse events
Smolis-Ba˛k et al (2015)3
Prospective randomized observation
n = 52
Sample: HF of ischemic or other etiology, NYHA FC III
Male sex: EX: 25 (96.1%); C: 44 (84%)
Age: EX = 60 ± 8.5 y
C = 65 ± 8.2 y
EF %: EX: 25 ± 7; C: 25 ± 7
Dropouts: NR
EX: Initial aerobic exercise training in the hospital setting (3 wk), continued training at home with telemonitoring. Large and small muscle isometric exercises, respiratory exercises, ROM exercises both in hospital and at home up to 3 mo (n = 26).
C: Hospital rehabilitation (3 wk) but no exercise program after discharge (n = 26).
4 mo:
Exercise capacity
Peak o 2, mL/kg/min Exercise time, min METs 6MWD, m
Exercise capacity (EX vs C)
↑Peak o 2: 3.8 ± 4.05, P = .03
↑Exercise time: 2.7 ± 2.8, P = .007
↑METs: 1.3 ± 1.8, P = NS
↑6MWD: 35 ± 103, P = NR
↑NHP-EL: 0.2 ± 0.9, P = NS
↓NHP-LM: −0.8 ± 1.3, P = .03
Adverse events: NR
Zeitler et al (2015)46
3 groups, prospective RCT
n = 2331
Sample: Outpatients with HF and LVEF ≤35%, NYHA II-IV; CRT-D or ICD: n = 1118; CRT-D: n = 435; ICD: n = 683; no device: n = 1213
Male sex: 783 (64.5%)
Female sex: 430 (35%);
CRT-D: 94 (22%)
Age: 58 y (49-67 y)
CRT-D = 61 y
EF %: 25 ± 21
No device 20%; CRT-D 17.1%
EX: Supervised CR 18 sessions × 40 min/5× per wk at 60%-70% of HRR, followed by home exercise 5×/wk × 40 min at 60%-70% of HRR for 2-4 y
EX: n = 224
C: No restrictions on activity, n = 211
3 mo; median change:
Exercise capacity
Exercise time, min
Peak o 2, mL/kg/min
Adverse events
Composite of all-cause death or hospitalization
Exercise capacity (EX vs C)
Ex time:
↑ICD: 1.0
↑CRT: 1.1
↑No device: 1.2, P = NS
Peak o 2:
↑ICD: 1.0
↑CRT: 1.3
↑No device: 1.2, P = NS
KCCQ total score:
↑ICD: 4
↑CRT: 9, P = NS;
↑No device: 7
Adverse events:
All-cause mortality: EX vs C: HR = 1.18, P = NS
All-cause death or hospitalization: EX vs C: HR = 1.05, P = NS
Abbreviations: AT, anaerobic threshold; C, control; CR, cardiac rehabilitation; CRT, cardiac resynchronization therapy; CRT+ and CRT−, patient with and without CRT, respectively; CV, cardiovascular; EF, ejection fraction; EX, exercise; HF, heart failure; HF+ and HF−, patients with and without CRT, respectively; HR, hazard ratio; HRR, heart rate reserve; ICD, implantable cardioverter defibrillator; KCCQ, Kansas City Cardiomyopathy Questionnaire; LBBB, left bundle branch block; LV, left ventricle; LVEF, left ventricular ejection fraction; METs, metabolic equivalents; MLHFQ, Minnesota Living with Heart Failure Questionnaire; NHP-EL, Nottingham Health Profile-Energy Level; NHP-LM, Nottingham Health Profile-Limited Mobility; NR, not reported; NS, not significant; NYHA FC, New York Heart Association functional classification; QOL, quality of life; RCT, randomized controlled trial; ROM, range of motion; o2, oxygen uptake; Wpeak, peak Watts; 6MWD, 6-minute walk distance.

Table 3 - Studies Included With Ventricular Assist Device Implantation
Study Design, n Sample Age, Mean ± SD Male Sex, n (%) EF%, Mean ± SD Dropouts Intervention Outcomes Results Exercise Versus Control Mean Change + SD
Laoutaris et al (2011)47
Prospective RCT
n = 15
Sample: Bridge to transplant with LVAD or BiVAD, 5.6 mo after implant, DCM
Male sex: 14 (93.3%)
Age: 38 ± 16 y
EF %: NR
Dropout rate: EX: 28.6%
EX: Moderate intensity aerobic exercise 45 min × 3-5×/wk for 10 wk + high intensity inspiratory muscle training 2-10 times/wk for 10 wk, walk every day (n = 10)
C: Walk every day (n = 5)
12 wk:
Exercise capacity
Peak o 2, mL/kg/min
Exercise time, min
6MWD (m)
Exercise capacity (EX vs C)
↑Peak o 2: 4.5 ± 4.3, P = NS
↑Exercise time: 1.7 ± 2.4, P = NS
↑6MWD: 79 ± 65, P = NS
Quality of life
↑MLHFQ: 12.6 ± 10, P = NS
Adverse events: None
Hayes et al (2012)48
Prospective RCT
n = 14
Sample: LVAD bridge to transplantation, 32 d after implant, 64% DCM
Male sex: 12 (85.7%)
Age: EX: 49 ± 14 y; C: 46 ± 15 y
EF %: EX: 16 ± 5; C: 13 ± 4
Dropouts: 0% both groups
EX: Aerobic exercise + strengthening + mobilization: 1 hr 3×/wk; HR at 50% peak o 2 × 8 wk (n = 7)
C: Mobilization, daily walking to Borg RPE = 13 (n = 7)
8 wk:
Exercise capacity
Peak o 2, mL/kg/min
6MWD, m
Exercise capacity (EX vs C)
↑Peak o 2: −0.5 ± 4.6, P = NS
↑6MWD: 42 ± 113, P = NS
Quality of life
↑SF-36 PCS: 6.0 ± 16.6, P = NS
↑SF-36 MCS: 5.8 ± 16.5, P = NS
Adverse events: None
Kugler et al (2012)49
Nonrandomized prospective study
n = 70
Sample: HF bridge to transplant, 6 wk after implant; ischemic cardiomyopathy; EX = 43.9%: C = 49.1%
Male sex:
EX: 60 (85.4%); C: 61 (87.5%)
Age: EX: 52 ± 2 y; C: 51 ± 2 y
EF %: NR
Dropouts: EX: 29.4%; C: 28.6%
EX: Dietary counseling + weight management + psychosocial counseling + home conditioning with bicycle using baseline CPET test (n = 34)
C: Usual care, no interventions (n = 36)
6 mo:
Exercise capacity
Peak o 2, mL/kg/min% predicted
Anxiety and depression
Exercise capacity (EX vs C)
↑Peak o 2: 4.5%, P = NR
↑SF-36 PCS: 1.0, P = NR
↓SF-36 MCS: −0.5, P = NR
Anxiety and depression
↓HADS-A: −1.9, P = NR
↓HADS-D: −0.5, P = NR
Adverse events: NR
Karapolat et al (2013)50 Retrospective pre-/post-design
n = 11
Sample: LVAD as a bridge to transplantation
Dilated HF, 54.6%
Male sex: 9 (85.7%)
Age: 45.57 ± 14.05 y
EF %: NR
Dropouts: NR
EX: Hospital aerobic exercise: 90 min × 3×/wk for 8 wk + flexibility exercises + strength exercises of upper and lower extremities) + relaxation exercises 8 wk:
Exercise capacity
Peak o 2
SF-36 PF
SF-36 MH
Anxiety and depression
Spielberger STAI
Exercise capacity (pre vs post)
↑Peak o 2: 0.45 ± 3.5, P = .93
↑SF-36 PF: −18.1 ± 30.1, P = .85
↑SF-36 MH: −15.8 ± 15.4, P = .33
↓STAI state: 2.4 ± 4.8, P = .49
↓STAI trait: 5.3 ± 1.4, P = .35
↓BDI: 6.3 ± 6.7, P = .89
Adverse events: NR
Kerrigan et al (2014)17
Prospective RCT
n = 26
Sample: Continuous-flow LVAD implanted 1-6 mo
Male sex: 19 (73%)
Age: EX: 53 ± 13 y; C: 60 ± 12 y
EF %: EX: 21 ± 7; C: 21 ± 9
Dropouts: EX: 11.1%; C: 12.5%
EX: CR: aerobic exercise 30 min 3×/wk for 6 wk at 60%-80% of heart rate reserve (n = 18)
C: Usual care, no exercise prescription (n = 8)
6 wk:
Exercise capacity
Peak o 2 mL/kg/min
6MWD, m
Treadmill time. min
KCCQ summary score
Exercise capacity (EX vs C)
↑Peak o 2: 2.0 ± 0.3, P = .27
↑6MWD: 46.4 ± 70.6, P = .24
↑Treadmill time: 3.6 ± 2.5, P = .001
Quality of life
↑KCCQ: 10.0, P = .005
Adverse events: 1 ER visit due to VT causing syncope within 1 hr of exercise
Marko et al (2015)51Single group retrospective use of rehabilitation n = 41, outcomes only for n = 15 Sample: LVAD completing CR, 48 ± 38 d post-LVAD implantation; 71% had ICD
Male sex: 33% (80)
Age: 55 ± 12 y
Dropouts: NR
EX: Rehabilitation program, medical training therapy, walking and gymnastics, with goal of reaching Borg scale of 13
Aerobic training: 3 min cycling with no load at the beginning and at the end of the session; alternating periods of high and low intensity
Strength training: Training period: 32 d/person.
1 mo:
Exercise capacity
Peak o 2, mL/min/kg (n = 15)
Exercise capacity (pre vs post)
↑Peak o 2: 3.21 ± 4.66, P = .007
↑METs: 1 ± 1.35, P = .007
Adverse events: 1 nonsustained VT during cycling
Abbreviations: BiVAD, biventricular assist device; BDI, Beck Depression Inventory; CPET, cardiopulmonary exercise test; CR, cardiac rehabilitation; DCM, dilated cardiomyopathy; EF, ejection fraction; ER, ejection fraction; HADS-A, Hospital Anxiety Depression Scale-Anxiety; HADS-D, Hospital Anxiety Depression Scale-Depression; HF, heart failure; HR, heart rate; ICD, implantable cardioverter defibrillator; KCCQ, Kansas City Cardiomyopathy Questionnaire; LVAD, left ventricular assist device; METs, metabolic equivalents; MLHFQ, Minnesota Living with Heart Failure Questionnaire; NR, not reported; QOL, quality of life; RCT, randomized controlled trial; RPE, rating of perceived exertion; SF-36 MCS, Short Form-36 Mental Composite Score; SF-36 MH, Short Form-36 item Mental Health; SF-36 PCS, Short Form-36 item Physical Composite Score; SF-36 PF, Short Form-36 item Physical Function; STAI, Spielberger State-Trait Anxiety Inventory; o2, oxygen uptake; VT, ventricular tachycardia; 6MWD, 6-minute walk distance.

Data Extraction

Two authors independently extracted study characteristics from included studies, with a third author verifying all the data that were extracted. These data included (1) general information: title, authors' names, and year of publication; (2) methods: study design, total duration of study, study setting, and withdrawals; (3) participants: sample size, number randomized, number in control group, age, sex, baseline left ventricular ejection fraction (LVEF), and number of participants lost to follow-up; in addition, for an ICD device, we included type of ICD, indication for ICD, and time since device implanted; (4) interventions: type of exercise, type of rehabilitation program with components, setting (eg, outpatient, community, home setting or a combination), and type of control intervention; (5) outcomes: all outcomes specified and collected, and time points reported; and (6) bias (see quality assessment later).

Quality Assessment (Risk for Bias)

The quality of published randomized controlled trials (RCTs) included in this review was assessed using the Jadad Scale.52 The Jadad Scale is scored (0-5) on the basis of randomization, double blinding, and withdrawals or dropouts. The range of possible scores is 0 (low quality) to 5 (high quality). If an included study was not an RCT, no further assessment was done to determine study quality. Each study was scored on the basis of an additional rating system regarding hierarchy of evidence.53 To ensure the results of the systematic review are generalizable to the study population of interest, we reported on relevant aspects of the included studies in the review, including participant characteristics (age, sex, LVEF), sample size, and type and characteristics of the exercise intervention.



Studies were published between the years 1998 and 2016, with the majority of randomized studies being completed within the last decade. There were a total of 24 unique studies included in this review (ICD: 14, CRT 4, and VAD: 6). Of these, 14 employed an RCT design, 5 retrospective designs, 3 pre-/post-test designs, and 1 case-control and 1 prospective but nonrandomized design. Some of the studies of patients with an ICD include those with a CRT-D device. However, separate analyses for the CRT-D versus ICD were only rarely reported, making it difficult to discern the value of exercise interventions in the CRT population alone. The quality of studies was not considered when selecting studies for this review, but RCTs completed in the VAD population were of higher quality than those completed for either CRT or ICD groups. The average level of evidence for all studies was 3.0, indicating well-designed studies that were not necessarily randomized.


There were a total of 5308 study participants, of whom 2702 participated in exercise interventions, with a range of 10 to 2331 patients. The HF-ACTION study contributed the largest number of participants in both the ICD and CRT analyses.36,46 The average age of all study participants was 56.0 ± 10.1 years (range: 38-66 years). Those in the VAD population were younger than those with an ICD or CRT. The majority of participants were male and Caucasian. The average LVEF = 23.7% (range: 17%-29.4%); those with a VAD had lower LVEF at the time of study entry. The indication for the device was secondary prevention in the ICD population (64%), HF with bridge to transplant in the VAD population (100%), and HF with LVEF ≤35% in the CRT population (80%). Because more studies were conducted in ICD recipients, data from this population represent a larger percentage of the participants studied. Blinding of study participants was not possible, but blinding of outcome assessors not involved in the intervention was reported in 6 studies.


Regardless of device type, the duration of follow-up in most studies ranged from right after completion of the intervention up to 24 mo. The majority of studies reported the primary outcomes after completion of exercise training at 3 mo. Dropout rates from all studies averaged 17%; the range was 0% to 31%. Dropout rate was not reported in 3 ICD studies, 2 VAD studies, and 4 CRT studies. Adherence was not often reported; such reporting was limited to studies of patients with an ICD.


The majority of exercise interventions contained an aerobic component in the form of walking, cycling, running, or combinations of these. The duration of interventions ranged from 1.5 mo to 12 mo, the average duration was 3 mo, with 1 study reporting a 12-mo exercise intervention.36,46 Training programs varied in frequency (3-5 sessions per week), duration (30-90 min per session), and intensity (50%-90% of peak oxygen uptake [o2] HR or age-adjusted maximum HR). One study reported a yoga intervention in the ICD population. Exercise in the VAD population was always conducted within a supervised outpatient cardiac rehabilitation program. Resistance or strength training was used in 1 study in the VAD population51 and in 2 studies in the ICD population,37,3940 with no studies including a resistance exercise component in the CRT group. Resistance training in the VAD population included strength training of the lower extremities, while in the ICD population resistance training was implemented in 15- to 20-min sessions 1 to 2 times per week. Some studies used multicomponent interventions (support group, education, psychological interventions). The control condition was represented as “usual care” or no exercise recommendation in the RCTs. Significant others/partners were encouraged to attend study sessions as coparticipants in 1 study.39


Exercise Capacity

The primary outcome for the majority (20/24) of studies was peak o2 in mL/kg/min that was assessed with a cardiopulmonary exercise test (CPET). Exercise training resulted in an average increase in peak o2 of 2.6 mL/kg/min, (range: 2.2-3.2). These increases were statistically significant when compared with the usual care or a comparison group.

QoL and Psychological Outcomes

A total of 15 studies report QoL outcomes (6 ICD, 5 VAD, and 4 CRT), and 10 studies reported anxiety and/or depression outcomes (7 ICD, 2 VAD, and 1 CRT). The impact of exercise interventions on these outcomes was most often not statistically significant. In the ICD group, exercise significantly improved QoL in 1 study and 2 each for anxiety and depression. In the VAD group, QoL increase was significant in 2 studies, and in 1 study, depression was significantly reduced. In the CRT population, QoL was significantly improved in 1 study and depression was not significantly changed in any study.

Adverse Events

The majority of studies carefully reported adverse events such as ICD therapies (shocks, antitachycardia pacing), device complications, arrhythmias, and deaths that occurred during exercise or the follow-up period. Adverse events in the CRT studies were often not reported. During exercise training or exercise testing, ICD shock events were very low (2.2% in ICD, 1.1% in VAD, and not reported in CRT). Death rates were reported in only a few studies: ICD = 1 (no deaths related to exercise) and CRT = 1 (all-cause mortality not significant). In the ICD group, 5 of 14 studies reported hospitalization rates over the follow-up period that ranged from 13% to 67%. Hospitalization was not reported in the VAD studies. A composite endpoint of hospitalization and death rate was reported in the CRT group, with hospitalization rates being higher in CRT (26%) than in no CRT (15%).


Implantable Cardioverter Defibrillator


There were 14 unique studies of exercise interventions that included 2681 patients, of whom 1353 exercised (see Supplemental Digital Content Table 1, available at: https://links.lww.com/JCRP/A61). There were 7 RCTs, 2 retrospective studies, 3 pre-/post-studies, and 1 each of a prospective nonrandomized study or case-control study. Two studies had multiple publications of differing outcomes using the same sample.39–43 These articles were counted only once in the review. The average JADAD score of the RCTs was 2.8 (moderate quality), with average level of evidence = 3.0. The studies completed in the earlier years were of lower quality than those completed in the most recent 5 years.

The average age of the ICD group was 59.7 ± 10.7 years, range: 54 to 66 years. The majority of participants were male (75%), with an average LVEF = 29.4%. The length of time from ICD implant to the start of the exercise intervention ranged from 1 to 36 mo; the average was 14 mo. Four studies enrolled first-time ICD recipients within 1 to 1.5 mo following ICD implant. The indication for ICD implantation was secondary prevention in 64% of the studies, with 1 study not reporting ICD implant indications. The CRT-D devices were included in 4 of 14 studies.

The duration of exercise interventions ranged from 2 mo to 12 mo—the average was 3 mo. Duration of the exercise intervention was 3 mo in 8 studies, 2 mo in 5 studies, and 6 or 12 mo in 1 study each. The majority of studies used training at moderate to high levels of intensity, that is, at 60% to 90% of maximum HR attained during the CPET or based on age-adjusted estimated maximum HR (12 of 14). Two studies included a resistance exercise component implemented in addition to the aerobic component, while 3 studies contained psychological and/or educational components. Duration of exercise sessions ranged from 30 min to 90 min of walking, cycling, and/or isometric exercises. Most exercise programs were completed in the supervised outpatient setting (11 of 14) and 2 of 14 were completed entirely at home. One study reported on yoga exercise that consisted of breathing techniques, postures and poses, and meditation. The dropout rate from the exercise studies ranged from 0% to 31%; the average was 15.8%, and dropout rate was not reported in 3 studies.

Exercise Capacity

The majority of studies (9 of 14) reported exercise outcomes using CPET data, with peak o2 as the primary outcome. On average, the difference between exercise training and control groups for peak o2 after completion of exercise was 2.4 mL/kg/min. Sixty percent of studies reported that this difference was significantly improved over usual care. One study reported results of the shuttle walk test that improved after exercise training, while 1 study found that steps per day after 3 mo of a home walking program significantly increased.

QoL and Psychosocial Outcomes

Six studies reported QoL outcomes and 7 studies reported anxiety and/or depression outcomes. Exercise resulted in improved QoL in 1 study and had no significant effects in the others. Significant reductions in anxiety were noted in 2 studies, while 2 studies reported significant reductions in depression. The study using a yoga intervention reported several other psychological outcomes such as patient acceptance, emotions, self-compassion, interpersonal support, and ICD shock anxiety, the majority of which were not changed by the intervention.39

Adverse Events

Adverse events associated with exercise were reported in 12 of 14 studies. Three studies reported death rates, from which only 1 death was reported. This death was due to a noncardiac comorbidity. The percentage of ICD shocks reported during exercise or within a short time post-exercise ranged from 0% to 20%; average ICD shock rate was 2.2%. Implantable cardioverter defibrillator shocks during the follow-up period not related to exercise also ranged from 0% to 20%. Three investigations reported cardiac arrhythmias during exercise testing, with no arrhythmias noted in 1 study, 1 incident of ventricular tachycardia that did not require an ICD shock, and 1 incident of ventricular fibrillation cardiac arrest that required 2 ICD shocks. Taken together, the number of ICD shocks associated with exercise testing was very low. For the 2 studies that specifically reported antitachycardia pacing during exercise, the rate ranged from 1.1% to 2.2%. The hospitalization rates of those in exercise interventions ranged from 13% to 67%. The highest hospitalization rates over 12 mo following exercise were reported in the HF-ACTION trial.46 The remaining 4 studies reported hospitalization rates, averaging 20% in the follow-up period.


The quality of exercise training studies conducted in the ICD population is moderate, with earlier studies focusing primarily on safety and effects on peak o2. This literature suffers from small sample sizes, a predominance of male participants, variability in training volumes from moderate to high, most conducted in outpatient supervised cardiac rehabilitation, and unclear reporting of data, with no numerical or P values provided. Few intervention studies have tested resistance exercise interventions (n = 2) or contained psychoeducational components (n = 3).

Cardiac Resynchronization Therapy


There were a total of 4 studies of exercise interventions that included 2447 patients, of whom 1217 exercised (see Supplemental Digital Content Table 2, available at: https://links.lww.com/JCRP/A62). There were 4 RCTs, with an average JADAD score of 2.5 (moderate quality) and an average level of evidence = 3.0. The duration of the exercise intervention ranged from 3 to 5 mo (average was 3.6 mo). Most studies used training at moderate to high levels of intensity at 60% to 90% of maximum HR attained on the CPET. Exercise sessions ranged from 30 to 90 min of walking, cycling, or static large and small muscle isometric exercises. None of the studies included isotonic strength training. One study reported on static exercise only. The dropout rate from the exercise studies was not reported in 3 studies and was 18% in 1 study.

The average age of the CRT group was 60.7 ± 5.9 years (range: 59-64 years). The majority of participants were male (83%), with an average LVEF = 24.8%. The sample sizes of the studies ranged from 11 to 2231 patients; most studies contained <25 patients. The majority of CRT devices were CRT-D devices with defibrillation capability. There was 1 large trial (HF-ACTION)50 that is the largest exercise training study completed in HF patients. This study accounted for the majority of the sample size of all pacemaker trials reported.

Exercise Capacity

On average, the difference between exercise and control groups in peak o2 after completion of the exercise program was 3.2 mL/kg/min. This difference was significant when compared with usual care. One study also reported 6-minute walk distance and showed a nonsignificant improvement after exercise training.

QoL and Psychosocial Outcomes

Four studies reported QoL and 1 study reported depression outcomes after exercise interventions. Exercise resulted in improved QoL in 1 study and had no effect on depression in 1 study. Therefore, exercise had few significant effects on either QoL or depression outcomes. Anxiety in CRT exercise trials was not reported.

Adverse Events

Adverse events associated with exercise were not reported in 4 of 5 studies. One study reported no lead dislodgement and normal thresholds on the LV lead. One study delayed the start of exercise interventions until 3 mo after CRT implantation to avoid possible LV lead dislodgement.


The quality of exercise studies conducted in the CRT population is moderate but suffers from small sample sizes, a predominance of male participants, variability in training volumes from moderate to high, and unclear reporting of data, with no numerical or P values provided. No studies tested isotonic resistance exercise interventions or psychoeducational components.

Ventricular Assist Device


There were 6 studies of exercise interventions (see Supplemental Digital Content Table 3, available at: https://links.lww.com/JCRP/A63) that included 169 patients, of whom 121 exercised. There were 3 RCTs and 3 retrospective studies of those participating in cardiac rehabilitation. The average JADAD score of the RCTs was 5.0 (high quality), with level of evidence = 3.5. The duration of the exercise interventions ranged from 6 to 12 wk, 1 study reporting 18-mo outcomes. Most studies used training at moderate-level intensity 50% to 80% of maximum HR achieved on the CPET or ratings of perceived exertion of 13 using the Borg Scale. Exercise sessions ranged from 30 min to 90 min of walking, cycling, inspiratory muscle training, or gym exercises. One study included a strength training component. The dropout rate was 17.3% on average, ranging from 0% to 29%.

The average age of the VAD group was 47.5 ± 13.8 y, range: 38 to 58 y. The majority of participants were male (85%), with an average LVEF = 17%. The sample sizes ranged from 11 to 41 patients, and most studies included <20 patients. All patients received a VAD as a bridge to transplant.

Exercise Capacity

On average, the difference in peak o2 between exercise and control groups after completion of exercise was 2.2 mL/kg/min. Half of the studies reported that this difference was significantly improved versus usual care. Two studies measured 6-minute walk distance and showed nonsignificant changes after exercise training.

QoL and Psychosocial Outcomes

Five studies report QoL outcomes and 2 studies report psychological outcomes. Exercise resulted in improved QoL in 2 of 5 studies and reduced anxiety and depression in 1 study each. Therefore, exercise had equivocal effects on QoL and psychological outcomes.

Adverse Events

Adverse events associated with exercise were reported in 2 studies with 1 event of ventricular tachycardia that developed during training in each study; 1 episode resulted in syncope that required an emergency room visit and the other episode of ventricular tachycardia occurred during cycling and was nonsustained.


The quality of exercise studies conducted in the VAD population is high but suffers from small sample sizes, a predominance of male participants, low training volumes (which would be appropriate for this group relative to the ICD group), unclear reporting of data with no numerical or P values provided, and VAD participants who received the device for bridge to transplant only. The cost of the intervention delivery and monitoring, as well as adverse events in this population, has not been described.


This systematic review contains studies that tested at least 1 outpatient exercise intervention in persons who had a CID: ICD, CRT, or VAD. The most important finding is that moderate to strenuous exercise is safe and effective in improving cardiopulmonary outcomes with few adverse events. Albeit modest, the improvement noted in peak o2 following exercise training in these populations was on average 2.6 mL/kg/min. Adverse events such as ICD shocks, cardiac arrhythmias, lead dislodgement, and VAD pump issues were very low during exercise testing and training in all studies. Although fewer investigations have been conducted in the VAD and CRT populations, the results support that exercise is safe and efficacious. This is in contrast to a recent review published by Bajaj and Biswas54 that suggested that there was an increased relative risk of adverse events in those who exercised with an ICD compared with those without an ICD (OR: 2.63, P = .01). However, this analysis considered total adverse events, not only those associated with exercise, some of the calculations were flawed and the comparison group did not have an ICD.

The primary outcome assessed in the majority of all exercise studies was peak o2 collected during CPET. While this outcome has been used as the “gold standard” for assessing changes in maximum or peak o2 and physical capacity associated with exercise training, this test is expensive, physically demanding for patients, and poses risks to patients with CIDs. In addition, this outcome does not convey important information related to the ability to perform activities of daily living, work, ambulate without symptoms, care for oneself, and participate in activities that promote independence. Future studies involving exercise in the CID population should consider the use of the 6-minute walk distance, muscle strength, gait and balance, or total daily physical activity (pedometer/accelerometer data) as important primary outcomes.

The effect of exercise training on QoL and psychological outcomes in the CID population was reported in less than one-third of all studies. In these reports, exercise interventions had a small or no effect on improving QoL and psychological outcomes. Some investigations reported these outcomes despite not including a specific educational/psychological intervention that was part of the exercise program. This may have accounted for the null findings. In addition, individuals engaging in exercise after implantation of a CID are often debilitated or suffering from cardiac-related symptoms that limit QoL, thus the reason for receiving the device. Exercise alone cannot improve all cardiac-related symptoms, thus limiting the ability to detect these differences at follow-up. Future studies testing exercise interventions should include psychological components at least in the ICD (ICD alone or CRT-D) population, where fear of receiving an ICD shock during exercise prohibits many from exercising.55

The majority of exercise interventions were conducted in Caucasian male participants, with few women and other ethnic populations included. With the exception of 1 study,44 no investigations reported outcomes by sex or ethnic groups. However, these studies enrolled the individuals who were available to them at the time who had a particular device implanted. None of the investigations aimed to enroll individuals with a specific type of device and were not involved in the selection or management of the device during the exercise interventions or follow-up. In the future, if CID implantation includes an equal number for sex and racially diverse populations, studies should enroll a more equivalent number from these groups.

The majority of exercise interventions were implemented in outpatient cardiac rehabilitation settings, with few interventions extended into the home setting. Training volumes in most of the studies were not reported and are difficult to quantify, but most were prescribed to progressively increase workloads over 2 to 3 mo, as tolerated. The exact volume of exercise that is required to produce an incremental increase of 1 mL/kg/min in maximal/peak o2 is unknown. In addition, it is not known whether small increases in peak o2 are perceptible to patients, or whether exercise conveys benefits in conducting other ADLs that might matter most. Future studies should include important patient-reported outcomes that are identified and valued by the patients who are interested in participating in exercise interventions.

In the ICD population, many more investigations of exercise interventions have been tested with the largest number of participants. Initially, the major question to be answered was whether or not exercise could be performed without increasing the number of cardiac arrhythmias or cardiac arrests. For future studies, the important next steps are to bring the exercise interventions developed in clinical trials to more diverse populations of patients with ICDs in routine care settings, to adapt protocols for widespread use, and to provide education to clinicians about how to prescribe and monitor exercise safely. For those who receive an ICD shock either before or during exercise, strategies for determining how to respond to these events while supporting continuation in activities are yet to be defined. As well, psychological support strategies to reduce fear and anxiety regarding exercise in routine practice need to be implemented and tested, so that more individuals with an ICD are willing to undertake exercise and activity interventions that can lead to higher QoL post-implant.

The CRT population includes individuals with a CRT-P or a CRT-D. Some CRT-D patients have been included in studies of exercise in HF, but few investigations have included only those with the CRT-P. The total number of individuals participating in exercise interventions with CRT is small. The additional benefit of exercise training after receipt of a CRT device has not been specified (ie, effects on LV remodeling, ejection fraction, reduction in QRS duration, or relief of cardiac symptoms). The programming parameters of the CRT device in terms of atrial ventricular delays and optimization protocols may contribute significantly to its benefits and could improve exercise performance if standardized. Future exercise investigations should determine the additional benefits of CRT over no CRT, after a standard waiting period from implant has passed.

In the VAD population, exercise interventions have been tested only in a small number of participants who have a VAD for bridge to transplant. The VAD exercise studies have included a younger population than those receiving an ICD or CRT. Implantation of the VAD itself does not improve heart function and can limit the amount of moderate to high intensity exercise that can be accomplished. As VAD technology evolves and improves, higher flow rates or configurations may allow some patients to participate at higher levels of exertion, particularly in those who are younger. For future studies, including exercise for those with a VAD as a destination therapy, measuring outcomes that involve daily activity and functioning, testing interventions that strengthen skeletal muscle and improve mobility, and involvement of a significant partner are needed. As well, those who have transitioned from VAD to heart transplant have not been included in exercise interventions that promote return to physical function. These recommendations are in agreement with those of Jung and Gustafsson,20 who also noted that the VAD group is more debilitated at the initiation of exercise interventions and the VAD itself limits the ability to achieve certain exercise outcomes.

Finally, little has been written about the techniques, costs, protocols, and expert knowledge needed to test and implement exercise in the CID population. In addition, the role of contextual factors, such as medications, comorbidities, cardiac diagnoses, age, and others, on the design and evaluation of exercise interventions has not been well described.


This systematic review has inherent strengths and limitations. The review offers a comprehensive overview of all studies completed to date in the peer-reviewed published literature. While the total number of patients participating in the exercise studies is relatively small (∼5000), conclusions about the safety and preliminary efficacy can be drawn from the review. With small sample sizes, the variability in outcomes can be large, and thus finding statistically significant differences is more difficult. However, the overall signal that exercise training improves exercise capacity over no training is evident in the preponderance of studies. As well, exercise is safe and is related to few adverse outcomes in the CID groups.

Some data were extracted from both RCTs and observational studies. Follow-up times for participants were of short duration, with little data on long-term efficacy and safety provided (ie, few studies report data up to 12 mo or beyond). The methodological quality of studies that were not RCTs was not scored. The JADAD Scale scores were used, but no other components of intervention fidelity measurement or design integrity were assessed. Cardiac rehabilitation was the intervention tested in several studies, but the total dose of exercise and components of the cardiac rehabilitation varied from individual to individual. The timing in starting exercise interventions ranged from 1 mo after a CID to several years later. Mortality as an outcome was not measured in many trials and is not comparable between studies.

Like any other literature review, the values of systematic reviews require clear reporting of information available from included studies. Further details about participant attendance and compliance rates for exercise-based rehabilitation programs were inadequately reported. This limited how thoroughly these topics can be addressed. Finally, this systematic review has the potential for publication bias. We conducted an exhaustive search to ensure that we had identified all relevant studies including trials with negative results. However, the “gray” literature (eg, reports, working papers, government documents, white papers, or evaluations) was not extensively included in this review.


Exercise interventions tested in the CID population (ICD, CRT, and VAD) indicate that exercise training at moderate to high intensity is safe and effective in improving cardiopulmonary outcomes without adverse events. Future investigations should include a more diverse sample of participants, the destination therapy VAD population, designs that include translation of exercise to routine practice, and measurement of costs and patient-centered outcomes.


1. Belardinelli R, Capestro F, Misiani A, Scipione P, Georgiou D. Moderate exercise training improves functional capacity, quality of life, and endothelium-dependent vasodilation in chronic heart failure patients with implantable cardioverter defibrillators and cardiac resynchronization therapy. Eur J Cardiovasc Prev Rehabil. 2006;13(5):818–825.
2. Rogers JG, Aaronson KD, Boyle AJ, et al. Continuous flow left ventricular assist device improves functional capacity and quality of life of advanced heart failure patients. J Am Coll Cardiol. 2010;55(17):1826–1834.
3. Smolis-Ba˛k E, Da˛browski R, Piotrowicz E, et al. Hospital-based and telemonitoring guided home-based training programs: effects on exercise tolerance and quality of life in patients with heart failure (NYHA class III) and cardiac resynchronization therapy. A randomized, prospective observation. Int J Cardiol. 2015;199:442–447.
4. Hussein NA, Thomas MA. Rehabilitation of patients with implantable cardioverter/defibrillator: a literature review. Acta Cardiol. 2008;63(2):249–257.
5. Gururaj AV. Cardiac resynchronization therapy: effects on exercise capacity in the patient with chronic heart failure. J Cardiopulm Rehabil. 2004;24(1):1–7.
6. Dougherty CM, Glenny RW, Burr RL, Flo GL, Kudenchuk PJ. Prospective randomized trial of moderately strenuous aerobic exercise after an implantable cardioverter defibrillator. Circulation. 2015;131(21):1835–1842.
7. Hansen D, Dendale P, Berger J, Meeusen R. Rehabilitation in cardiac patients: what do we know about training modalities? Sports Med. 2005;35(12):1063–1084.
8. Zusterzeel R, Spatz ES, Curtis JP, et al. Cardiac resynchronization therapy in women versus men. Circ Cardiovasc Qual Outcomes. 2015;8(2 suppl 1):S4–S11.
9. Zhang Q, Yu CM. Could exercise unveil the mystery of non-response to cardiac resynchronization therapy? [Editorial]. Europace. 2011;11:768–769.
10. Birnie DH, Tang AS. The problem of non-response to cardiac resynchronization therapy. Curr Opin Cardiol. 2006;21(1):20–26.
11. Zhang J, Hobkirk J, Carroll S, Pellicori P, Clark AL, Cleland JG. Exploring quality of life in patients with and without heart failure. Int J Cardiol. 2015;202:676–684.
12. Yu CM, Wing-Hong Fung J, Zhang Q, Sanderson JE. Understanding nonresponders of cardiac resynchronization therapy—current and future perspectives. J Cardiovasc Electrophysiol. 2005;16(10):1117–1124.
13. Conraads VM, Vanderheyden M, Paelinck B, et al. The effect of endurance training on exercise capacity following cardiac resynchronization therapy in chronic heart failure patients: a pilot trial. Eur J Cardiovasc Prev Rehabil. 2007;14(1):99–106.
14. Giannuzzi P, Temporelli PL, Corrà U, Tavazzi L; ELVD-CHD Study Group. Antiremodeling effect of long-term exercise training in patients with stable chronic heart failure: results of the Exercise in Left Ventricular Dysfunction and Chronic Heart Failure (ELVD-CHF) Trial. Circulation. 2003;108(5):554–559.
15. Kirklin JK, Naftel DC, Kormos RL, et al. Fifth INTERMACS annual report: risk factor analysis from more than 6,000 mechanical circulatory support patients. J Heart Lung Transplant. 2013;32(2):141–156.
16. Jaski BE, Lingle RJ, Kim J, et al. Comparison of functional capacity in patients with end-stage heart failure following implantation of a left ventricular assist device versus heart transplantation: results of the experience with left ventricular assist device with exercise trial. J Heart Lung Transplant. 1999;18(11):1031–1040.
17. Kerrigan DJ, Williams CT, Ehrman JK, et al. Cardiac rehabilitation improves functional capacity and patient-reported health status in patients with continuous-flow left ventricular assist devices: the Rehab-VAD randomized controlled trial. JACC Heart Fail. 2014;2(6):653–659.
18. Ueno A, Tomizawa Y. Cardiac rehabilitation and artificial heart devices. J Artif Organs. 2009;12(2):90–97.
19. Bajaj RR, Biswas A, Oh P, Alter DA. Safety of implantable cardioverter defibrillators in exercise therapy and cardiac rehabilitation: a systematic review and meta-analysis. Can J Cardiol. 2015;31(10):S264–S265.
20. Jung MH, Gustafsson F. Exercise in heart failure patients supported with a left ventricular assist device. J Heart Lung Transplant. 2015;34(4):489–496.
21. Isaksen K, Morken IM, Munk PS, Larsen AI. Exercise training and cardiac rehabilitation in patients with implantable cardioverter defibrillators: a review of current literature focusing on safety, effects of exercise training, and the psychological impact of programme participation. Eur J Prev Cardiol. 2011;19(4):804–812.
22. Cornelis J, Beckers P, Taeymans J, Vrints C, Vissers D. Comparing exercise training modalities in heart failure: a systematic review and meta-analysis. Int J Cardiol. 2016;221:867–876.
23. Hsu CY, Hsieh PL, Hsiao SF, Chien MY. Effects of exercise training on autonomic function in chronic heart failure: systematic review. BioMed Research Int. 2015;2015:591708.
24. Ostman C, Jewiss D, Smart NA. The effect of exercise training intensity on quality of life in heart failure patients: a systematic review and meta-analysis. Cardiology. 2016;136(2):79–89.
25. Giuliano C, Karahalios A, Neil C, Allen J, Levinger I. The effects of resistance training on muscle strength, quality of life and aerobic capacity in patients with chronic heart failure—a meta-analysis. Int J Cardiol. 2017;227:413–423.
26. Floegel TA, Perez GA. An integrative review of physical activity/exercise intervention effects on function and health-related quality of life in older adults with heart failure. Geriatr Nurs. 2016;37(5):340–347.
27. Shea BJ, Grimshaw JM, Wells GA, et al. Development of AMSTAR: a measurement tool to assess the methodological quality of systematic reviews. BMC Med Res Methodol. 2007;7:10.
28. Shea BJ, Bouter LM, Peterson J, et al. External validation of A Measurement Tool to Assess Systematic Reviews (AMSTAR). PLoS One. 2007;2(12):e1350.
29. Shea BJ, Hamel C, Wells GA, et al. AMSTAR is a reliable and valid measurement tool to assess the methodological quality of systematic reviews. J Clin Epidemiol. 2009;62(10):1013–1020.
30. Fitchet A, Doherty PJ, Bundy C, Bell W, Fitzpatrick AP, Garratt CJ. Comprehensive cardiac rehabilitation programme for implantable cardioverter-defibrillator patients: a randomised controlled trial. Heart. 2003;89(2):155–160.
31. Frizelle DJ, Lewin RJ, Kaye G, et al. Cognitive-behavioural rehabilitation programme for patients with an implanted cardioverter defibrillator: a pilot study. Br J Health Psychol. 2004;9(3):381–92.
32. Vanhees L, Kornaat M, Defoor J, et al. Effect of exercise training in patients with an implantable cardioverter defibrillator. Eur Heart J. 2004;25(13):1120–1126.
33. Davids JS, McPherson CA, Earley C, Batsford WP, Lampert R. Benefits of cardiac rehabilitation in patients with implantable cardioverter-defibrillators: a patient survey. Arch Phys Med Rehabil. 2005;86(10):1924–1928.
34. Dougherty CA, Glenny R, Kudenchuk PJ. Aerobic exercise improves fitness and heart rate variability after an implantable cardioverter defibrillator. J Cardiopulm Rehabil Prev. 2008;28(5):307–311.
35. Fan S, Lyon CE, Savage PD, Ozonoff A, Ades PA, Balady GJ. Outcomes and adverse events among patients with implantable cardiac defibrillators in cardiac rehabilitation: a case-controlled study. J Cardiopulm Rehabil Prev. 2009;29(1):40–43.
36. Piccini JP, Hellkamp AS, Whellan DJ, et al. Exercise training and implantable cardioverter-defibrillator shocks in patients with heart failure. JACC Heart Fail. 2013;1(2):142–148.
37. Smialek J, Lelakowski J, Majewski J. Efficacy and safety of early comprehensive cardiac rehabilitation following the implantation of cardioverter-defibrillator. Kardiol Pol. 2013;71(10):1021–1028.
38. Toise SC, Sears SF, Schoenfeld MH, et al. Psychosocial and cardiac outcomes of yoga for ICD patients: a randomized clinical control trial. Pacing Clin Electrophysiol. 2014;37(1):48–62.
39. Berg SK, Moons P, Christensen AV, Zwisler AD, Pedersen BD, Pedersen PU. Clinical effects and implications of cardiac rehabilitation for implantable cardioverter defibrillator patients: a mixed-methods approach embedding data from the Copenhagen Outpatient Programme-Implantable Cardioverter Defibrillator Randomized Clinical Trial With Qualitative Data. J Cardiovasc Nurs. 2015;30(5):420–427.
40. Berg SK, Zwisler A-D, Koch MB, et al. Implantable cardioverter defibrillator specific rehabilitation improves health cost outcomes: findings from the COPE-ICD randomized controlled trial. J Rehabil Med. 2015;47(3):267–272.
41. Christensen AV, Zwisler AD, Svendsen JH, et al. Effect of cardiac rehabilitation in patients with ICD: are gender differences present? Results from the COPE-ICD trial. Pacing Clin Electrophysiol. 2015;38(1):18–27.
42. Isaksen K, Munk PS, Valborgland T, Larsen AI. Aerobic interval training in patients with heart failure and an implantable cardioverter defibrillator: a controlled study evaluating feasibility and effect. Eur J Prev Cardiol. 2015;22(3):296–303.
43. Isaksen K, Munk PS, Giske R, Larsen AI. Effects of aerobic interval training on measures of anxiety, depression and quality of life in patients with ischaemic heart failure and an implantable cardioverter defibrillator: a prospective non-randomized trial. J Rehabil Med. 2016;48(3):300–306.
44. Lau ET, Thompson EA, Burr RL, Dougherty CM. Safety and efficacy of an early home-based walking program after receipt of an initial implantable cardioverter-defibrillator. Arch Phys Med Rehabil. 2016;97(8):1228–1236.
45. Patwala AY, Woods PR, Sharp L, Goldspink DF, Tan LB, Wright DJ. Maximizing patient benefit from cardiac resynchronization therapy with the addition of structured exercise training: a randomized controlled study. J Am Coll Cardiol. 2009;53(25):2332–2339.
46. Zeitler EP, Piccini JP, Hellkamp AS, et al. Exercise training and pacing status in patients with heart failure: results from HF-ACTION. J Card Fail. 2015;21(1):60–67.
47. Laoutaris ID, Dritsas A, Adamopoulos S, et al. Benefits of physical training on exercise capacity, inspiratory muscle function, and quality of life in patients with ventricular assist devices long-term postimplantation. Eur J Cardiovasc Prev Rehabil. 2011;18(1):33–40.
48. Hayes K, Leet AS, Bradley SJ, Holland AE. Effects of exercise training on exercise capacity and quality of life in patients with a left ventricular assist device: a preliminary randomized controlled trial. J Heart Lung Transplant. 2012;31(7):729–734.
49. Kugler C, Malehsa D, Schrader E, et al. A multi-modal intervention in management of left ventricular assist device outpatients: dietary counselling, controlled exercise and psychosocial support. Eur J Cardiothorac Surg. 2012;42(6):1026–1032.
50. Karapolat H, Engin C, Eroglu M, et al. Efficacy of the cardiac rehabilitation program in patients with end-stage heart failure, heart transplant patients, and left ventricular assist device recipients. Transplant Proc. 2013;45(9):3381–3385.
51. Marko C, Danzinger G, Käferbäck M, et al. Safety and efficacy of cardiac rehabilitation for patients with continuous flow left ventricular assist devices. Eur J Prev Cardiol. 2015;22(11):1378–1384.
52. Jadad AR, Moore RA, Carroll D, et al. Assessing the quality of reports of randomized clinical trials: is blinding necessary? Control Clin Trials. 1996;17(1):1–12.
53. Melnyk B, Fineout-Overholt E. Evidence-Based Practice in Nursing and Healthcare: A Guide to Best Nursing Practice. 3rd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2015:11.
54. Bajaj RR, Biswas A. safety aspects of implantable cardioverter defibrillators in patients participating in exercise therapy: a systematic review and meta-analysis. Int J Phys Med Rehabil. 2016;4(4). doi:10.4172/2329-9096.1000344.
55. Sears SF, Kirian K. Shock and patient-centered outcomes research: is an ICD shock still a critical event? Pacing Clin Electrophysiol. 2010;33(12):1437–1441.

cardiac rehabilitation; exercise; implantable cardioverter defibrillator; pacemaker; VAD

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