Probably the most widely discussed and controversial topic in cardiac rehabilitation has been, and continues to be, the degree of monitoring and supervision required for patients of Phase II/III cardiopulmonary rehabilitation programs (CRPs). Phase II/III practices currently range from no continuous telemetered electrocardiographic monitoring (CTEM) for any patients1,2 to use of CTEM for 3 weeks to 6 months for patients who have undergone percutaneous transluminal coronary angioplasty (PTCA).3-6 Many programs routinely use CTEM on all Phase II patients for up to 36 exercise sessions, regardless of the individual level of cardiovascular risk. Because of variations in published risk stratification criteria, variations in the definitions of Phase II, III, and IV programs, individual beliefs on degree of monitoring, and the certainty that some high-risk patients will remain clinically high risk for years, the length and type of cardiovascular monitoring for risk stratified patients has become a clouded issue. The degree of monitoring and supervision appears to vary by the facility, even in states with well-defined CRP guidelines.6-10 This is due to many factors, including: (1) patient cost for CTEM ranging from $30-$110 per session; (2) a lack of data on the optimal duration of electrocardiographic (ECG) monitoring before independent cardiac exercise; (3) the qualifications and number of staff available for supervision; (4) individual beliefs for risk stratification; (5) current Medicare and insurance reimbursement patterns; and (6) the uncertainty of proposed health-care practices and reimbursement patterns in the future.
Currently, only 11% to 15% of cardiac patients actually participate in a formal supervised CRP,11,12 with a 30% to 40% dropout rate within the first 6 months.13 Given these dismal statistics, unsupervised gymnasium or home exercise programs (with or without transtelephonic ECG monitoring) is advocated for low to moderate risk patients if accessibility to a formal CRP is impractical.14-21 The use of transtelephonic exercise monitoring for patients who exercise at home, in community centers, or in university settings has become more prevalent and may provide for greater participation for patients of all risk strata. Low-risk patients with myocardial infarction and patients with coronary artery bypass graft (CABG) surgery can exercise safely, improve aerobic capacity, and receive other beneficial effects from a home or gymnasium program.16,17,20-26 It is recommended that home exercisers be properly screened and have periodic re-evaluation of their cardiac risk factors.1,20,27 Although unsupervised exercise has been recommended by some for patients who may be considered at high risk,28,29 including those with chronic heart failure,30 the risks and/or benefits of unsupervised exercise in the home or gymnasium setting for high-risk patients have not yet been thoroughly examined.31 There are also legalities that must be considered for all cardiac patients who engage in unsupervised exercise programs.15,32,33 Disadvantages to unsupervised exercise are that patients often become noncompliant with home exercise or fail to perform exercises appropriately because of a lack of regular feedback from CRP staff on proper exercise procedures. Patients who perform home exercise also miss the group camaraderie, group and staff support, and the ongoing cardiac disease education associated with a formal CRP. The pros and cons of unsupervised cardiac exercise are presented in Table 1.
Risk stratification has enhanced patient classification in CRPs based on the likelihood of future cardiac events, making it easier to determine who should have closer monitoring and supervision. Guidelines, position statements, and risk stratification classifications presented by the American Association of Cardiovascular and Pulmonary Rehabilitation (AACVPR),34 American College of Sports Medicine (ACSM),35,36 American College of Cardiology (ACC),37 American College of Physicians (ACP),38 American Heart Association (AHA),39 the Department of Health and Human Services,40 the North Carolina Cardiopulmonary Rehabilitation Association (NCCRA),10,41 and others have provided useful recommendations for cardiovascular monitoring in CRPs. However, because of the variation in definitions of cardiovascular risk presented by these and other organizations and the ambiguity regarding CTEM in patients of varying risk strata, there still remains wide discrepancy in monitoring/supervision practices among CRPs. In the 1995 AACVPR “Guidelines for Cardiac Rehabilitation Programs”34 and the U.S. Department of Health and Human Services' “Clinical Practice Guidelines for Cardiac Rehabilitation,”40 broad minimal guidelines for ECG monitoring are presented which encourage risk stratification and patient self-monitoring. However, issues specific to risk stratification and duration of ECG monitoring are not addressed. Monitoring in CRPs has been discussed extensively14,42-49 and due to a wide variation in beliefs and practices, many of these issues may never be fully resolved or result in overall program uniformity.
To address monitoring and safety issues, North Carolina developed state-wide standards of practice, which include vocational, psychosocial, nutritional, and exercise therapies in 1983 (revised in 1995)10 and a peer review process is currently used to certify and recertify CRPs. Programs may be awarded either full certification status, provisional certification status, or have their certification suspended or revoked if they fail to assure patient safety with proper emergency procedures or fail to adhere to proper monitoring/supervision standards. Specifications for emergency equipment and procedures are well-defined in the rules and coincide with guidelines presented by the AACVPR,34 ACSM,35 and AHA.39,40 The minimal standards for monitoring and supervision of Phase II/III programs in North Carolina are stated as follows:10
- Rule.0507(B) “At the discretion of the medical director, the patient may be monitored continuously or intermittently through the use of electrocardiography while performing the exercise therapy” (page 14).
- Rule.0507(D) “A minimum of two staff members must be present during the exercise therapy session. A staff-to-patient ratio in the exercise therapy session shall be at least 1:10. A staff-to-patient ratio in a telemetry-monitored exercise therapy session shall be at least 1:4” (page 14).
- Rule.0903(A) “Two medical personnel must be present during the exercise therapy session. The medical personnel must consist of the supervising physician and at least one additional medically trained person, who has the written approval of the medical director” (page 23).
Given the wide range of practices that have been derived from these rules, a special task force of the NCCRA has developed a more detailed framework for monitoring and supervision of Phase II/III CRPs based upon current literature and trends. These recommendations have been reviewed and approved by the Exercise Science and Executive committees, which consists of staff members from many North Carolina CRP's. The information provided in this paper does not supersede or substitute for any part of the published state guidelines and should be viewed as recommended rather than absolute guidelines. For the purposes of this paper, we have adapted the definitions of the various phases of cardiac rehabilitation (Phases II-IV) from the AACVPR guidelines34 and Hall.50
Phase II (immediate outpatient): Physician-referred exercise and behavior change therapy that is ideally initiated within 2 to 3 weeks after hospital discharge. Phase II programs may use intensive monitoring and supervision, including ECG monitoring for some patients.
Phase III (intermediate outpatient): Physician-referred exercise and behavior change that begins when the patient has stabilized and that does not require continuous or frequent intermittent ECG monitoring. There is a continued emphasis on endurance exercise training and behavior change at this level. Phase III has less supervision than Phase II and more supervision than Phase IV.
Phase IV (maintenance outpatient): The staff have determined that the patient's ability to maintain achieved outcomes and continue to work on optimal health practices under minimal surveillance is sufficient.
This paper will not address Phase IV monitoring and supervision guidelines, as these have been presented elsewhere.41 In North Carolina, Phase II programs often are conducted for 8 to 12 weeks, although some patients may require longer intensive monitoring and/or supervision. Phase III often encompasses the period of 12 weeks to 1 year. Phase IV is often categorized as the maintenance period after 1 year of formal CRP participation. It should be noted that these time definitions are broad and will vary by the program.
Risks of Exercise Training
To analyze the need for monitoring and supervision in CRPs, the level of risk of untoward events associated with exercise must first be examined. Sudden cardiac death with exercise is rare in apparently healthy populations and is usually the result of congenital abnormalities or cardiomyopathies (often hypertrophic cardiomyopathy) in persons <35 years of age and coronary artery disease (CAD) in persons >35 years of age.39,51-53 The vast majority of sudden cardiac death cases are arrhythmic in origin.44,54,55 Exercising with undetected CAD, rather than exercise alone, is usually the precipitator of potentially lethal arrhythmias and/or sudden death.52,56 From the early 1960s to late 1970s, untoward events were reported during vigorous exercise in joggers, runners,56-60 and patients of cardiac exercise programs.55,61,62 Between 1975 and 1980 Thompson and colleagues56 reported 1 death for every 7,620 male joggers aged 30 to 64. This was equal to an hourly death rate seven times greater than that observed during more sedentary activities. However, if men with known CAD were excluded, the death rate dropped to only 1 death per year for every 15,200 joggers. Larger retrospective studies have shown the incidence of cardiac arrest or sudden death during exercise to be extremely low in both apparently healthy63-66 and cardiac67-70 populations. Kohl and co-workers52 summarized the results of these and other studies and reported mortality rates ranging from 0.0 to 2.0 per 100,000 person-hours for apparently healthy individuals who performed both low- and high-intensity exercise.
Strenuous physical activity has been shown to be associated with a transient increase in the risk of acute myocardial infarction in habitually sedentary populations.55,68,71,72 Many have speculated that habitual exercise provides protection against the triggering of myocardial infarction.68,71-75 Willich and colleagues72 reported that men and women who exercised less than 4 times per week had a relative risk of myocardial infarction of 6.9, whereas those who exercised >4 times per week had a relative risk of only 1.3. Similarly, Mittleman and associates71 found that the more one exercised, the lower the risk of acute myocardial infarction. Men and women who exercised <1, 1-2, 3-4, or >5 times per week had a relative risk of myocardial infarction of 107, 19.4, 8.6, and 2.4, respectively. In 1984, Siscovick and associates68 reported similar findings showing that while risk of cardiac arrest is transiently increased during vigorous exercise, men who performed habitual vigorous exercise had a 40% lower relative risk of cardiac arrest compared to sedentary men. In this study, the risk of having a cardiac arrest during exercise was 56 times greater for sedentary men, yet only 5 times greater during exercise for men who had high levels of habitual physical activity (>140 minutes per week). In 1989, Blair and colleagues75 reported a low relative risk (28%) of having a fatal cardiac arrest for individuals who exercised regularly compared to those who did not. Thus, physical activity may lower the level of cardiovascular risk in habitually active populations. Most agree that exercise is very safe for healthy populations and properly screened cardiac participants and that the benefits of exercise clearly outweigh the risks.
Exercise Complications in Cardiac Patients
In general, well-designed studies of exercise complications in CRP participants are few and have shown varied results. Earlier studies reported cardiac arrest rates ranging from approximately 1/6,000 patient-hours to 1/32,000 patient-hours of exercise.55,61,62,69,76-81 In a 13-year retrospective study of CRP participants, Hossack and Hartwig55 reported 25 cardiac arrests in 2,464 patients during 374,616 hours of supervised exercise (overall incidence of 1 arrest per 14,985 hours) at the Cardiopulmonary Research Institute (CAPRI) rehabilitation program between 1968 and 1981. Of these arrests, 16 occurred during exercise and 9 during the cool-down period. All occurred in males and 100% were successfully resuscitated. Of the 25 arrests, 12 occurred in patients who had been enrolled >12 months. Similar rates of cardiac arrest during CRP exercise have been reported by Fletcher and Cantwell62 (1 arrest per 15,000 hours of exercise) and Leach and coworkers78 (1 arrest per 12,000 hours). Hossack and Hartwig55 determined that the three greatest predictors of cardiac arrest were: (1) marked ST-segment depression on the ECG; (2) an above average exercise capacity; and (3) a record of poor compliance with exercise intensity guidelines (i.e., intensity violators). Data from Schuler and associates82 reinforce the finding that intensity violators are at greater risk of developing cardiovascular complications, as they reported that three patients who exceeded their prescribed target heart rate zone developed life-threatening arrhythmias during exercise.
In one of the largest reported surveys of multiple centers, Haskell69 accumulated data on 13,570 CRP participants from 30 programs between 1960 and 1977 (1,629,634 patient-hours of supervised exercise). In this study, 61 major cardiovascular complications were reported that included 50 cardiac arrests and 7 myocardial infarctions. The incidence of cardiovascular complications from these centers was lower than previously reported: 1 arrest per 32,593 exercise hours; 1 myocardial infarction per 232,809 exercise hours; and 1 fatality per 116,402 exercise hours (mortality rate of 0.61 per 100,000 hours of exercise). The overall complication rate (fatal and nonfatal) was 1 event for every 26,715 patient-hours. Forty-two (84%) of the 50 subjects who suffered a cardiac arrest were successfully resuscitated. Forty of 61 (66%) major complications occurred during either warm-up or cool-down exercise. The two programs which reported using CTEM for all patients during exercise had an overall complication rate (fatal or non-fatal) of 1 event per 117,333 patient-hours of exercise, significantly lower than the 28 programs that did not conduct CTEM which averaged 1 event for every 22,028 patient-hours of exercise. Haskell69 speculated that the lower complication rates observed in the programs that used CTEM may have been because of other program characteristics, such as closer medical supervision of lower exercise intensities.
In 1986, Van Camp and Peterson67 reported significantly fewer cardiovascular complications during exercise than had previously been reported. These investigators reported a total of 29 complications during CRP exercise (21 cardiac arrests and 8 myocardial infarctions) which included 3 fatal events during 2,351,916 hours of outpatient exercise training. This was equivalent to 1 cardiac arrest per 111,996 patient-hours (8.9 arrests per 1,000,000 exercise hours); 1 myocardial infarction per 293,990 patient-hours (3.4 infarctions per 1,000,000 hours of exercise, similar to Haskell's data); and 1 fatality per 783,972 patient-hours of exercise (1.3 fatalities per 1,000,000 exercise hours or a mortality rate of 0.13 per 100,000 hours of exercise). Combining the 21 cardiac arrests and 8 myocardial infarctions yielded an overall complication rate of 1 per 81,101 patient-hours of exercise. Of the 21 patients who experienced a cardiac arrest, 18 (86%) were successfully resuscitated. Twelve of 20 cardiac arrests (60%) occurred during the exercise session, 6 (30%) occurred during the immediate recovery period, and 2 (10%) occurred 30 to 60 minutes after the exercise session.44 There was no significant difference in the frequency of events among Phase II-IV patients considering either the size of the program, the extent of ECG monitoring, or compliance to exercise. Furthermore, of the 167 separate programs in the study, 144 (86%) reported no major cardiovascular complications during the study period of 1980-1984. Similar nonfatal complication rates in cardiac patients have been reported by Shephard and colleagues70 at the Toronto Rehabilitation Centre (1 cardiac arrest per 113,583 patient-hours of exercise) and Meyer43 from Cardiac Treatment Centers (1 complication per 122,000 patient-hours of exercise).
From these investigations, it appears that mortality rates in CRPs range from 0.13 to 0.61 per 100,000 person-hours of supervised cardiac exercise.52,67,69 This is equivalent to 3 deaths per 2,351,916 person-hours67 and 10 deaths per 1,629,634 person-hours69 of exercise, respectively. Thus, it appears that although the risk of having a serious cardiac event may be increased slightly during supervised exercise, the risk of sudden death is not greater for CRP participants. Greenland and Pomilla46 performed a weighted average of cardiac risk in CRPs from 8 studies that indicated 1 fatality per 386,908 patient hours of exercise or a mortality rate of 0.26 per 100,000 patient-hours, which is similar to mortality rates reported in studies of apparently healthy exercisers.56,64 Haskell81 determined from previously cited studies that the risk of having a cardiac arrest during supervised CRP exercise is only once every 4 years. Clearly, the incidence of cardiac arrest has decreased among CRP participants from the 1960s to the 1980s. Whether having patients continuously ECG monitored improves patient safety and reduces the risk of cardiovascular complications has not been formally studied and remains to be seen.
The incidence of exercise related cardiovascular complications have been reported to be low in North Carolina and California programs that use little or no CTEM. At the Wake Forest CRP in Winston-Salem, North Carolina, 11 cardiovascular complications requiring physician assistance have occurred during supervised exercise in more than 1,700 patients (mean age 62 years) between 1975 and 1995.2 These were as follows: eight instances of cardiac arrest (all successfully resuscitated); two instances of sudden onset bradycardia; and one myocardial infarction (post-exercise). Of these complications, nine occurred in Phase IV (maintenance) participants and two occurred in Phase II participants. This program typically enters Phase II or “beginner” patients 3 to 6 weeks after a cardiac event and retains a large number of these patients in their maintenance program. No fatalities have been reported in this CRP since its inception. This particular program does not use CTEM, but rather performs intermittent “quick-check” defibrillator ECG checks on a daily or weekly basis for most patients. Medical supervision (staff-to-patient ratio of at least 1:10) is provided by exercise physiologists, a nurse, graduate students and an attending physician.83 The finding at Wake Forest that cardiovascular complications can occur as or more frequently in Phase IV (maintenance) participants as in Phase II participants has been supported by others.44,55,67,82 At the Mecklenburg Cardiac Rehabilitation Center in Charlotte, North Carolina, six exercise-related complications requiring physician assistance and/or emergency medical team response have occurred in more than 2,000 Phase II-IV patients between March 1984 and December 1995 (unpublished data). These were three instances of myocardial infarction resulting from acute thrombosis of angioplastied vessels in early morning exercise sessions and one myocardial infarction and two instances of cardiac arrest in afternoon sessions. All cardiac arrests and one myocardial infarction occurred during prescribed target exercise and two myocardial infarctions occurred during cool-down exercises. Each case was handled successfully and all occurred in Phase IV participants. In this program, CTEM is used only for selected high risk Phase II patients (usually for a maximum of 2 to 3 weeks) and no patients were using CTEM at the time of their complications. At the Cardiac Therapy Foundation of Palo Alto, California (formerly YMCArdiac Therapy), CTEM has never been used for any Phase II-IV patients, including those considered to be at high risk. This program uses intermittent “quick-look” ECG checks for patients as necessary based on observed signs and symptoms. Four cardiac arrests have occurred during exercise in this program over a 25-year period and all patients were successfully resuscitated. Thus, it is clearly evident that properly supervised CRPs can operate safely with little or no use of CTEM.
ECG Monitoring in Cardiac Rehabilitation
Cardiac rehabilitation should be initiated soon after hospital discharge in a safe environment and should include assessment and risk factor education in the areas of psychology, nutrition, exercise, and vocational pursuits.10,34,84 Overall, patients with CAD run a greater risk of cardiac events than the normal population and some have reported a lifetime risk of sudden cardiac death as high as 50%.85,86 Ambulatory ECG recordings of cardiac patients (including those classified as “low-risk”) have shown frequent periods of silent ischemia during everyday activities at heart rates lower than the ischemic threshold from graded exercise testing.87,88 Ventricular dysrhythmias and ST-segment depression are often prevalent during everyday activities and patients are often asymptomatic at the time of these events.40,89,90 Moreover, there is a 25% chance of graft occlusion during the first year following coronary artery bypass grafting.91 Because those with CAD run a greater risk of having a cardiac event associated with exercise, some have surmised that all patients with CAD are at “high risk,” especially those who have had angioplasty-type procedures.5,92 These patients typically have shown a high rate of restenosis (up to 50%) within the first 6 months following PTCA or other revascularization procedures such as directional atherectomy, rotational ablation, laser, or stents.93-97 Given this, recommendations for CTEM up to 6 months for PTCA patients have been made5,6 because of: (1) the relatively high rate of restenosis within 6 months after PTCA; (2) the increasing use of PTCA by interventional cardiologists; (3) the unpredictability of restenosis following PTCA; (4) the substantial evidence showing significant disease progression in dilated and nondilated arteries; and (5) the potential trauma to the intima and media of the coronary artery during angioplasty-type procedures and the increased likelihood of plaque rupture. Moreover, cardiovascular complications can occur as frequently in longstanding maintenance participants who have had revascularization procedures as in patients who have recently entered a CRP.2,55,67
Duration and Degree of ECG Monitoring
The most common techniques currently used for ECG monitoring are: (1) CTEM by hardwire or telemetry; and (2) intermittent ECG monitoring by either “quick-look” assessment with defibrillator paddles, periodic rhythm strips, or periodic telemetry monitoring.34,98,99 The purposes of CTEM are to: (1) act as a “safety net” to detect potentially malignant cardiac rhythms that can be treated before symptoms or other complications develop; (2) insure that the patient remains within their prescribed target heart rate range; and (3) provide continuous feedback on heart rate and rhythm to the CRP staff. Malignant dysrhythmias are more likely to be detected by CTEM over several training sessions than during graded exercise testing alone.100-102 The pros and cons of CTEM are presented in Table 2.
Although 7 to 12 weeks of CTEM has previously been recommended due to the potential risk of exercise related untoward events,43,89 others feel that 2 to 4 weeks of CTEM is adequate for most patients.4,19,39,42,103 Some authors have taken the position that CTEM should be limited to moderate to high47 or high-risk patients only.38,46,104 In the 1995 AHA Exercise Standards position paper, three activity classifications with CTEM recommendations for each have been designated (Table 3).39 Electrocardiographic monitoring for apparently healthy individuals is not required, whereas ECG monitoring for low-risk, moderate-risk, and high-risk cardiac patients is recommended for at least 6 to 12 sessions. The AHA feels that all low-risk patients with known, stable CAD should have ECG monitoring and medical supervision for at least 6 to 12 sessions during the early prescription phase of training, although the fewest possible sessions should be used.19,39 For moderate- to high-risk patients, CTEM and medical supervision is recommended for 6 to 12 sessions or more, or until the patient understands safe activity levels and the CRP staff have determined that exercise is well-tolerated and effective. The patient must also be able to self-monitor pulse rate and symptoms adequately. The ACC37 has recommended that identifiable high-risk patients who have the characteristics in Table 4 be supervised and have CTEM. However, there is no recommendation on how long monitoring should be used.
The AACVPR34 has presented minimal guidelines for ECG monitoring that encourages intensive monitoring (i.e., CTEM or intermittent ECG monitoring) when clinically appropriate, progression to less intensive monitoring, self-monitoring instruction, and routine patient evaluation. However, specific risk stratification and duration of monitoring issues are not discussed. In the 1995 Clinical Practice Guidelines for Cardiac Rehabilitation, ECG monitoring issues are addressed to an even lesser extent and the reader is referred to other position papers and guidelines for recommendations. Because cardiovascular complications appear unrelated to the elapsed time postcardiac event,2,44,55,67,82 some authors5 have recommended extended CTEM over many weeks to “catch” potentially dangerous arrhythmias. However, the efficacy of this approach may be costly to the patient and its value may be limited.4 Most feel that monitored sessions should include symptom assessment by staff, blood pressure measurements, rating of perceived exertion by the patient, and instruction for equipment use.11,19,34,39 (Note: the degree to which blood pressure should be monitored during CRP sessions has not been studied. It is likely that too much blood pressure monitoring may increase patient dependency on staff services and lessen patient self-efficacy.)
To evaluate the optimal amount of ECG monitoring, one must consider the risk level of the individual to be monitored. This is determined by many factors, including the extent of disease, the past clinical history, disease progression, and overall left ventricular function. Most will agree that those at greatest risk of cardiovascular complications have multiple risk factors, severe CAD or continuing myocardial ischemia, recurrent ventricular arrhythmias, angina or ischemia during exercise, a marked reduction in left ventricular systolic function, exertional hypotension, a low exercise capacity (<5 METS), or combinations thereof.39,105-107 Those classified as moderate to high risk by the AACVPR,34 ACSM,35 or AHA39 require special considerations and should always be monitored for: (1) signs or symptoms of changing health status; (2) medication adherence that may adversely influence quality of life; (3) influences of coexisting metabolic or orthopedic problems that may affect exercise compliance; and (4) physician follow-up of ventricular function, myocardial ischemia, dysrhythmias, and functional capacity.107 This committee feels that judicious use of CTEM may be efficacious for providing information on some of these variables. Continuous telemetered electrocardiographic monitoring may be especially useful for those who cannot self-monitor heart rate because of physical or intellectual impairment or those who have not previously had a graded exercise test or pharmacological stress test. For these individuals, CTEM could assist with evaluation of cardiac responses during daily exercise to help further refine the exercise prescription until a stress test is performed.
Only a small number of studies have attempted to shed light on the optimal duration and degree of ECG monitoring for risk stratified patients. In 1982, Fardy and colleagues89 reported a 16% dysrhythmia rate during the first 7 weeks of Phase II exercise, which decreased to 13% during the following 5 weeks. Thirteen percent of the patients in this investigation had an onset of dysrhythmias during the last 5 weeks of the program. Based on these findings, Fardy and colleagues89 concluded that cardiac exercise monitoring for patients with recent events was justified and recommended a minimum monitoring period of 7 to 12 weeks. However, a small sample size was used in this study. In 1984, Mitchell and coworkers42 recommended a shorter ECG monitoring period of 4 weeks for patients post-cardiac event based on a low incidence of arrhythmias and complications observed during exercise, provided they had undergone careful preliminary screening. Grall and colleagues108 conducted a 5-year (1987-1991) retrospective study of 241 patients who had undergone CABG, PTCA, or who had a previous myocardial infarction and concluded that CTEM is especially useful during the first 3 weeks of Phase II exercise, although there was no mention of the types of complications or arrhythmias detected. In the largest retrospective study of cardiac complications, Van Camp and Peterson44 found that patients who experienced cardiac arrest in programs with CTEM had more abnormal risk profiles than patients who were monitored intermittently with ECG. However, these same authors67 found no difference in the incidence of cardiac arrest, myocardial infarction, or sudden death during exercise between monitored and unmonitored patients in Phase II, III, or IV programs. From these data, Van Camp and Peterson concluded that CTEM may not be required for low- or even moderate-risk CRP participants.
In 1984, Meyer43 reported that the relatively low cost of CTEM was modest when compared with other therapeutic modalities used in cardiovascular disease. He justified the patient cost of CTEM by reasoning that exercise heart rates could be constantly updated over time, lending to an optimal training effect for the CRP participant which could promote earlier return to work for a lower financial cost to the patient and insurance companies. However, using weighted averages from earlier published data, Greenland and Pomilla46 concluded that the risk of having a cardiac event in a CRP is so remote (i.e., 1 fatal cardiac arrest every 107 years) that using CTEM over many sessions would not be cost-effective. Furthermore, the charge to the patient and insurance companies for CTEM has increased significantly over the years and some centers charge up to $110 for each telemetered session. Recent data from Keteyian and colleagues4 support the premise that extended use of CTEM is not cost effective. These investigators found that only 4 of 289 patients (1.4%) required a change in medical therapy as a result of CTEM during CRP sessions. Moreover, no major cardiovascular complications were observed in patients with CTEM during the 10-month study period. Thus, although some advocate using CTEM for extended periods, this would not appear to be warranted from either a cost4,46,109 or complication rate2,4,44,67,69 standpoint.
Clearly, indiscriminate monitoring of all patients for extended periods is not warranted. It would seem more practical and cost-effective to monitor selected moderate to high-risk patients who participate in Phase II programs with CTEM for shorter time periods (1-4 weeks) or until exercise hemodynamic responses are well documented. Charging higher prices for a greater number of CTEM sessions has substantially increased the cost of cardiac rehabilitation to the CRP participant and third-party carriers. With impending health care reform, these trends will surely have to change and CTEM will most likely be further scrutinized. Currently, short-term CTEM can be useful for detecting worrisome dysrhythmias or adverse cardiac events at a cost savings for the CRP participant and third-party carriers. Regarding these issues, Van Camp47 has stated: “It is likely that programs with continuous ECG monitoring increase the margin of safety, but they probably are not necessary for most low-risk or even moderate-risk patients. If only intermittent ECG monitoring is available in a program, lower exercise intensities for high-risk patients is necessary to provide an additional level of safety” (page 8).
Exercise Intensity and ECG Monitoring
The nature and degree of ECG monitoring should not only be determined by the patient's level of risk for exercise-related complications, but by the intensity of exercise as well.35,36,39 Higher risk patients may require more stringent ECG monitoring and staff supervision if they perform higher intensity exercise.
However, while high intensity exercise (70%-90% of ˙VO2max) appears to elicit significant cardiovascular benefits for the cardiac participant,110,111 there is now a trend toward lower exercise intensities (40%-50% of ˙VO2max) for cardiac patients.36,39,112 This is because of reported improvements in functional capacity, cardiovascular risk factors, cardiac function, psychosocial well-being, survival rate, and less risk of musculoskeletal injury with low-to-moderate exercise levels.75,112-115 Given this apparent trend, CRP staff may elect to provide less stringent ECG monitoring for patients who perform lower exercise intensities, including those who are considered to be at moderate-to-high risk of future cardiac events by established risk stratification criteria. However, this warrants further study.
Time of Day and ECG Monitoring
The time of day has been reported to be associated with cardiovascular risk and may also influence the degree of ECG monitoring during cardiac exercise. Ischemic and arrhythmic events appear to display a circadian variation with a peak occurrence in the early morning between 6 AM and noon.72,116-119 This may be related to: (1) morning surges of cortisol120 and catecholamines;121 (2) greater platelet aggregation;122 (3) increased vascular resistance with a morning surge in sympathetic vasoconstriction;123 and/or (4) an increase in heart rate or blood pressure124 that occurs in the morning compared to the afternoon. It is not clear whether these diurnal variations of ischemia are related to an increase in mental and physical activity, or a combination of both. Thus, is it necessary to provide stricter ECG monitoring and staff supervision in the morning classes than in the afternoon classes? Based on recent data from North Carolina and Georgia CRPs125 and others,66,126,127 this would not appear to be warranted. Murray and colleagues125 found that there was not a greater frequency of cardiovascular complications or dysrhythmias during morning cardiac exercise compared with afternoon exercise and concluded that both morning and afternoon hours are safe for CRP exercisers. Similarly, Siscovick and coworkers68 found no difference in the occurrence of cardiac events and time of day of exercise in their study of habitually sedentary and active men. Santolin and colleagues126 found no difference in hemodynamic or ECG responses in CRP participants who exercised either in the morning or afternoon hours and also concluded that it is safe for patients with CAD to exercise at any time during the day. Moreover, these authors found that tissue plasminogen activator levels increased significantly with both morning and evening exercise sessions and were significantly higher in the morning sessions than in the evening. Plasminogen activator inhibitor-Type 1 levels were also higher in the morning exercise sessions, but did not change significantly as a result of exercise. The combination of elevated tissue plasminogen activator levels and decreased plasminogen activator inhibitor-Type 1 levels favors fibrinolysis and reduces clot formation. These results have been supported in part by others in healthy127 and hypertensive128 subjects. Szymanski and Pate127 observed that tissue plasminogen activator was significantly elevated and that plasminogen activator inhibitor-Type 1 was significantly decreased with short duration, high intensity exercise (80% ˙VO2max) in young adult males. However, in contrast to the data of Santolin and colleagues,126 the evening exercise sessions showed more accentuated changes in fibrinolytic activity than did the morning sessions. Nevertheless, there was an apparent beneficial effect of both morning and evening exercise on fibrinolytic activity. Jimenez and associates128 determined that both basal fibrinolytic activity and peak fibrinolytic activity after isometric exercise were lower in the morning compared with the evening in hypertensive subjects. These investigators found no significant difference in blood pressure, heart rate, or platelet aggregability between morning and evening isometric exercise.
Based on these studies, the hypothesis that morning exercise may rupture vulnerable atherosclerotic plaque to initiate the coagulation process does not appear to be valid, although further research is necessary in cardiac populations. The higher incidence of morning cardiac events (6 AM to noon) reported by many investigators have generally not been related to exercise and may simply be a circadian variation. Exercise does not appear to increase platelet aggregability, but rather appears to provide a beneficial, clot-preventing increase in fibrinolysis. It currently appears to be safe for cardiac patients to exercise in a supervised setting at any time of the day, without the need of additional staff or ECG monitoring.
Monitoring for Resistive Exercise
Resistive exercise training has consistently been shown to be a very safe activity for CRP participants. Studies have shown that most patients can, and should, participate in some form of resistive exercise at all ages. Invasive and noninvasive studies of hemodynamic parameters during weightlifting,129-135 circuit weight training,136-141 and weight carrying or isodynamic activities142-147 all have shown that using low, moderate, or even high levels of resistance is physiologically safe and beneficial for many cardiac populations. Many studies provide evidence that resistive exercise testing and training can be initiated relatively early (2-8 weeks) after a cardiac event without adverse cardiovascular responses in properly screened, low- to moderate-risk patients.137,147-149 Properly administered isometric or isodynamic exercise has also been shown to be safe for many cardiac patients. Regarding these issues, the AHA150 has stated: “Careful isometric training alone or with aerobic training is generally safe and effective in patients with coronary disease who are medically stable and are in a supervised program” (page 340). Based on these data, there does not appear to be justification for additional cardiovascular monitoring than what would normally be provided in a CRP for those patients who participate in resistive or isodynamic exercise. However, one staff person should be designated to supervise the resistive training area during exercise sessions.131,151,152 Some studies have shown that resistive training is safe for higher risk patients in Phase II programs, including those with poor left ventricular function.129,148 However, further research is necessary to fully determine the potential risks, benefits, and the need for monitoring during resistive exercise in higher risk patients. General guidelines for cardiac resistive exercise have been presented elsewhere.34,35,131,151-153
Medical Supervision of Phase II/III Patients
Qualified allied health care personnel provide the supervision of CRP exercise sessions. In North Carolina, minimum standards require that two medically trained personnel (i.e., physician, nurse, or other ACLS certified staff) be present for all Phase II/III CRP sessions.10 These personnel must consist of the supervising physician, who may or may not necessarily be in the exercise area, and an additionally medically trained person (i.e., ACLS-trained nurse) who must be physically present in the exercise area in the event of complications. For hospital-based CRPs, a readily available emergency response team is permitted by state guidelines. The staff-to-patient ratio must be at least 1:10 for non-telemetered Phase II/III patients and at least 1:4 for ECG telemetered Phase II/III patients. (Note: some North Carolina programs routinely use greater staff supervision and CTEM for higher risk Phase III patients).
The required staff for operation of North Carolina CRPs includes the medical director/supervising physician, program director, exercise specialist, registered nurse, dietitian/nutritionist, mental health professional, and vocational rehabilitation counselor. Professional requirements for each of these positions have been outlined in the state guidelines.10 Any combination of these staff members that meets the required staff-to-patient ratios is acceptable, provided the supervising physician or an emergency medical team response is in close proximity to the exercise area (i.e., not in a different building or off the program campus area) and at least 1 medically trained person is involved with direct patient supervision. It should be noted that each program is required to have an ACSM-certified Exercise SpecialistSM or equivalent (i.e., American Physical Therapy Association Certified Cardiopulmonary Specialist) on staff to develop exercise prescriptions and assist with exercise leadership and supervision, which is in agreement with the AACVPR minimal qualifications for the CRP exercise specialist.34 Many North Carolina programs use staff from other disciplines (i.e., physical therapists, athletic trainers, graduate students, social workers, clergy) for additional expertise, a greater level of coverage, and a more well-rounded program. All personnel must be certified in Basic Life Support from the AHA, or equivalent.
The AHA39 position paper states that exercise sessions with moderate-to-high risk patients should be supervised by either a physician or an ACLS-trained nurse with standing orders from the physician. Less medical supervision for individuals with known, stable CAD who are at low risk of exercise complications is recommended by the AHA. For these patients, immediate supervision can be provided by a well-trained nurse working under a physician's standing orders.39 However, if a physician is not immediately available for monitoring of low-risk patients, the individual supervising the patients should have successfully completed an AHA sponsored course in ACLS and be able to administer emergency medications.39 (Note: This varies somewhat from the North Carolina guidelines, which state that a physician must always be one of the supervising personnel or an emergency medical response team be readily available for hospital-based programs). In general, the AHA guidelines state that medical supervision is required during the “prescription” exercise sessions and nonmedical supervision is sufficient for other exercise sessions, provided the patient understands proper self-monitoring during exercise. These standards are in agreement with those presented by the ACSM35 and AACVPR.34
The most important aspect of CRP supervision is safety. It is likely that lawsuits or repercussions resulting from untoward events in CRPs would ultimately fall back upon the medical director or supervising physician.84 Therefore, the medical director should take preventive steps in programs to maintain safety (i.e., maintain current ACLS certification, provide written physician standing orders, and assure adequate emergency procedures).84 Adequate personnel must always be readily available to handle untoward events for optimal emergency care. To optimize patient safety, participants of CRPs should be risk stratified and the highest risk patients should have the greatest level of supervision with the most highly trained personnel. Conversely, truly low-risk patients require less medical supervision. Table 5 presents the AACVPR recommendations for reducing cardiovascular complications in supervised CRPs.34
Based on the aforementioned review, the NCCRA recommends the following guidelines for monitoring and supervision practices in Phase II/III CRPs:
- Patients who enter a Phase II CRP who: (1) are classified as high risk by the AHA, ACSM/ACP, AACVPR, or other published risk stratification classifications; (2) meet ACC criteria for CTEM; (3) have not had a graded exercise or pharmacologic stress test; (4) cannot properly self-monitor heart rate due to physical or intellectual impairment; and/or (5) have selected or combined characteristics associated with exercise complications may require CTEM. There may also be other criteria that mandates judicious use of CTEM for some patients that the CRP medical director and staff will need to determine on an individual patient basis.
- Continuous monitoring for low- to moderate-risk patients is controversial and will vary by the patient and by the philosophy of the staff. Judicious use of CTEM should be used in all patients who have been risk stratified. It is currently not appropriate to require that all patients have CTEM who enter a Phase II program.
- If used, the duration of CTEM should be individualized to the patient and should generally not exceed 3 to 4 weeks (9-12 sessions). Extended CTEM can be costly to the patient and insurance companies, whereas, only selected patients benefit from it regarding adjustments in medical management. There appears to be no relationship between cardiovascular complications that occur during exercise and the time post cardiac event. It is inappropriate to indiscriminately monitor patients for many weeks. All patients considered for CTEM should be risk stratified, with the highest risk patients who meet the criteria in #1 receiving this service for the least number of sessions possible.
- The cornerstone of any monitoring system is competent, well-trained professional staff and many CRPs operate safely and effectively without the use of CTEM. If CTEM is not available, intermittent “quick-check” defibrillator monitoring (with ECG strip documentation capability) should be used on a daily and/or weekly schedule, depending on the risk level of the CRP participant. Intermittent ECG monitoring should be readily available for all patients during operation of Phase II/III programs.
- Staff of CRPs should record measurements of blood pressure, rating of perceived exertion (Borg 6-20 category scale or 0-10 category-ratio scale), and heart rates from radial pulse checks, “quick-check” defibrillator monitoring, or portable heart rate monitors during each exercise session, as applicable. Over-utilization of blood pressure monitoring may create an adverse patient dependency and may lower self-efficacy.
- The CRP medical director should assure safety standards by providing written physician standing orders (when appropriate) and verifying emergency protocols.
- No additional monitoring or supervision should be employed for morning CRP sessions than is required at other times during the day.
- Incorporation of resistive exercise for low- to moderate-risk cardiac patients does not necessitate additional or more extensive ECG monitoring or staff supervision. one staff person (i.e., exercise specialist or physical therapist) should be designated to supervise the resistive training area during all CRP sessions.
- Two medically trained personnel, including the supervising physician, need to be available for operation of all Phase II/III CRP sessions. In North Carolina, the supervising physician may or may not be directly involved in the exercise area. For hospital-based programs, an emergency medical team response is an acceptable alternative in case of untoward events.
- Each CRP must have at least one ACSM certified Exercise SpecialistSM or American Physical Therapy Association-Certified Cardiopulmonary Clinical Specialist on staff to develop exercise prescriptions, assist with exercise leadership, and train allied health staff.
- As with any aspect of cardiac rehabilitation, the amount of monitoring and supervision should be determined on an individual basis, based on severity of disease, risk classification, patient demographics, and the monitoring equipment available. Some higher risk patients may require more extensive CTEM for longer durations and these decisions should be made by the CRP staff and medical director on an individual patient basis. Overall, CTEM should be used very judiciously to avoid patient dependency, but should never be sacrificed when safety is a concern.
- In the 1990s, CRP staff must explore techniques that provide optimal outcomes with a cost-efficient and safe delivery system. Such techniques can facilitate lower expenses to the patient and insurance companies, better patient compliance, optimal monitoring/supervision, and more efficient program operation. Shorter duration CTEM on selected patients will certainly add to these cost savings.
- The most important type of monitoring system for any CRP is the astute observations of well-trained, professional staff.
Monitoring practices in CRPs in North Carolina and throughout the country will continue to vary by the program and by the philosophy of the staff. Although CTEM currently has a strong role in many CRPs, we feel that the “writing is on the wall” for significantly less usage of CTEM during supervised exercise in the future and that insurance carriers may be less likely to reimburse for programs that charge higher prices for this service. Using telemetry devices arbitrarily or excessively on patients who do not need ECG monitoring is inappropriate and may jeopardize future reimbursement for these services, create further dependency by the patient on the CRP staff, and defeat the purpose of cardiac rehabilitation. Large programs, such as Wake Forest in North Carolina and Palo Alto in California, who routinely enter moderate- to high-risk patients without the use of CTEM, have reported few untoward events and all have been handled successfully. However, further research is needed to assess the need for ECG monitoring and staff supervision for both aerobic and resistive exercise in higher risk or longstanding participants.
Using CTEM judiciously does have many advantages and CTEM can significantly enhance CRP operation by providing valuable information on ECG responses during exercise. Programs that do not use CTEM for higher risk patients should have greater staff supervision, prescribe lower exercise intensities, and use instantaneous ECG recordings from defibrillator monitors. Overall, CRP staff should focus on having the patients resume normal vocational and recreational activities as soon as possible after a cardiac event with as little dependence on cardiovascular monitoring as possible.
Should there be a greater level of medical supervision, cardiovascular monitoring, and emergency medical care for long-standing “maintenance” CRP participants who may technically be classified as low risk? This question can only be answered with research that examines the complication rates of longstanding CRP participants. It is now apparent that the maintenance participant may be at greater risk of having a subsequent cardiac events from increasing age and disease progression. The NCCRA believes that current risk stratification models need to be expanded to account for the risk of progression of the atherosclerotic process and future untoward events by including patient age, gender, duration of program participation, lipid status, blood pressure status, smoking status, and length of time from the initial cardiac event. Moreover, further studies are needed that randomize women and men of varying risk strata into programs with and without CTEM, using cardiac events as the major outcome variable. Currently, staff supervision for long-standing patients will continue to vary by the facility and philosophy of the staff.
These recommendations have been made to assist with monitoring and supervision practices of North Carolina CRPs. Hopefully, these guidelines can be of use for programs nationwide and can spur on further research in these very controversial areas.
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