Anesthesia, Blood Pressure, and Socioeconomic Status in Endovascular Thrombectomy for Acute Stroke: A Single Center Retrospective Case Cohort : Journal of Neurosurgical Anesthesiology

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Clinical Investigations

Anesthesia, Blood Pressure, and Socioeconomic Status in Endovascular Thrombectomy for Acute Stroke: A Single Center Retrospective Case Cohort

Hoefnagel, Amie L. MD*; Yao, Joyce MD, PhD*; Rao, Dinesh MD; Kovacs, Peter MD*; Brzezicki, Grzegorz MD, PhD; Mongan, Paul D. MD*

Author Information
Journal of Neurosurgical Anesthesiology 35(1):p 41-48, January 2023. | DOI: 10.1097/ANA.0000000000000790
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Abstract

Since 2015, reviews of randomized clinical trials (RCTs) showed that the use of second generation stent retriever devices within 6 hours of onset of symptoms of a large vessel anterior acute ischemic stroke (AIS) conferred significant benefits.1,2 Additional studies documented efficacy up to 24 hours with appropriate imaging and patient selection.3,4 Subsequently, modern mechanical thrombectomy (MT) stroke therapy utilizing second generation stent-retriever/aspiration devices has resulted in steady improvement of AIS outcomes as measured by successful reperfusion (modified treatment in cerebral ischemia [mTICI] ≥2b) and functional independence (modified Rankin Scale [mRS] 0 to 2).5

Still, the appropriate anesthetic for patients undergoing MT is debated. Meta-analysis of nonrandomized trials using first-generation thrombectomy devices reported an association of general anesthesia (GA) with worse clinical outcomes when compared with sedation/local anesthesia.6–10 Recent RCTs comparing GA and non-GA techniques (monitored anesthesia care [MAC]) and pooled analysis of these RCTs have reported variable outcomes when GA is compared with MAC.10–17 However, local patient populations may differ significantly from those enrolled into RCTs,18,19 and those differences may have considerable impact on outcomes. For example, racial disparities are significant; African Americans experience a higher prevalence and age adjusted death rate for stroke compared with non-Hispanic whites.20 Population differences are further emphasized by decreased access to MT based on ethnicity and insurance status.21,22 However, broad generalizations of race are insufficient to describe outcomes since geographic and socioeconomic status may be more important mediators of stroke outcomes.20,23,24

We retrospectively evaluated the impact socioeconomic deprivation25 and anesthesia care on clinical outcomes of 125 consecutive adult patients with large vessel AIS and extended ischemic times up to 24 hours treated with second generation MT devices at the University of Florida College of Medicine in Jacksonville. This institution is a level one trauma center and comprehensive certified stroke center with a mission to provide health care for all individuals, especially low-income and other vulnerable populations regardless of insurance or financial resources. Our primary objective was to determine whether anesthesia (GA vs. MAC) for MT impacted 90-day functional independence (mRS 0 to 2). Secondary outcomes included time to groin puncture, time to and successful arterial reperfusion (mTICI ≥2b), procedural blood pressure (BP), cerebral swelling, symptomatic intracranial hemorrhage, mortality, and the impact of BP and socioeconomic status on these outcomes.

METHODS

This study was approved by the University of Florida-Jacksonville Institutional Review Board (IRB201902760, 10/16/2019) as a retrospective chart review and was exempted from informed consent. Data were collected from 125 consecutive adults with anterior cerebral circulation occlusions (occlusion of the internal carotid artery and middle cerebral artery to the M3 segment) who had MT with or without IV recombinant tissue plasminogen activator (r-tPA) between January 2017 and June 2020. No industry funding supported this project, and this manuscript adheres to the Squire 2.0 guidelines for reporting quality improvement studies.

Institutional Stroke Care

Selection criteria for MT was based on clinical parameters, National Institutes of Health Stroke Scale (NIHSS), and imaging, with consideration of the time from onset of symptoms. Neurological impairment was assessed by a neurologist on admission using the NIHSS. A neuroradiologist reviewed all imaging to determine the Alberta Stroke Program Early CT (ASPECT) score and a RAPID automated CT perfusion score (iSchemaView Inc.) to quantify infarct core and penumbral volumes.

All MT interventions were performed by experienced interventional radiologists or endovascular neurosurgeons using a biplane imaging system in an interventional radiology (IR) suite. Endovascular MT was performed using stent retriever/aspiration catheters, either stand alone or in combination, with or without a balloon guide catheter depending on specific case or operator preference. Reperfusion grades were assessed using the mTICI perfusion scale (0—2a, unsuccessful recanalization; 2b—3, successful recanalization). Stroke related timepoints were recorded as part of the stroke workflow quality reporting. In case of a cervical internal carotid artery stenosis or occlusion, balloon angioplasty and stenting was performed as indicated.

Anesthetic Management

For patients not intubated before arriving in the IR suite, the anesthesia plan (GA or MAC) was established collaboratively between anesthesiologist and interventionalist depending upon anticipated complexity of the intervention and clinical status of the patient, including consideration of level of consciousness, ability to cooperate, agitation, airway obstruction, or airway protection concerns. GA occurred with rapid sequence induction and intubation unless the patient was already intubated in the emergency department. Ventilation was controlled in all GA patients to maintain a target end-tidal CO2 (ETCO2) >35 mm Hg. In patients receiving MAC, sedation was titrated according to clinical requirements and no airway adjuncts were used.

Systolic blood pressure (SBP) was maintained between 140 and 180 mm Hg; decreases in BP were treated with vasopressors to maintain SBP >140 mm Hg and avoid mean arterial pressure (MAP) <70 mm Hg. BP was recorded every 2.5 to 5 minutes from a noninvasive BP cuff or every minute if a radial arterial catheter was present.

Data Collection and Analysis

Individual chart review was performed to identify baseline demographics and outcomes of interest. Data were manually extracted from the EPIC electronic heath record and analyzed using SPSS v27 (IBM Corporation). Socioeconomic status was assessed with the area of deprivation index, a composite measure of socioeconomic deprivation.25

Descriptive statistics are expressed as median with interquartile range (IQR), or number and percentage as appropriate. The primary analysis was performed according to the intent-to-treat principle related to the initial choice of anesthetic (GA or MAC). Patient, anesthetic, procedural, and outcome variables were compared between GA and MAC groups using a Mann-Whitney U test for continuous variables and a χ2 or Fisher exact test for categorical variables. Parameters (patient, anesthetic, stroke, and thrombectomy) that had a P value <0.1 in a univariate analysis were sequentially entered into a dichotomous multivariate regression model to determine independent predictors of good (mRS 0 to 2) and poor (mRS 3 to 6) outcome. Statistical significance was defined as a 2-tailed P value <0.05.

RESULTS

This retrospective evaluation included 125 consecutive patients undergoing MT for AIS between 2017 and 2020. Patient demographics, clinical characteristics and IV r-tPA administration are shown in Table 1. Fifty-six patients received GA and 69 patients received MAC; 2 patients that converted from MAC to GA during MT remained assigned to the MAC group on the intent-to-treat analysis. The GA and MAC cohorts were well balanced; particularly, there was no difference in the area of deprivation index (P=0.16) or admission NIHSS which ranged between 4 and 29 in the MAC group and 4 and 31 in the GA group (P=0.47).

TABLE 1 - Baseline Demographic and Clinical Characteristics Stratified by General Anesthesia Versus Monitored Anesthesia Care
General Anesthesia (GA) Monitored Anesthesia Care (MAC)
N=56 N=69 P
Age (y) 65 (55-75) 68 (60-76) 0.27
Sex—female 28 (50.0) 28 (40.5) 0.29
Body mass index (kg/m2) 28.9 (23.6-35.6) 28.4 (25.0-32.3) 0.55
Race/ethnicity 0.30
 Black or African American 32 (57.1) 33 (47.9
 White 24 (42.9) 35 (50.7)
 White Hispanic 0 1 (1.4)
 Asian 0 0
Area of deprivation index percentile 74 (60-92) 72 (46-87) 0.16
 First quartile (0-25th %) 0 (0.0) 2 (2.9)
 Second quartile (26-50th %) 11 (19.6) 16 (23.2)
 Third quartile (51-75th %) 18 (32.2) 21 (30.4)
 Fourth quartile (76-100th %) 27 (48.2) 30 (43.5)
Smoking 17 (30.4) 17 (24.6) 0.47
Medication nonadherence 12 (21.4) 12 (17.3) 0.57
Hypertension 43 (76.8) 52 (75.4) 0.85
Chronic heart disease* 17 (30.3) 21 (30.4) 0.99
Atrial fibrillation 16 (28.6) 24 (34.8) 0.46
Prior stroke 19 (33.9) 20 (29.0) 0.55
Hyperlipidemia 31 (55.4) 31 (44.9) 0.25
Diabetes 24 (42.9) 22 (31.8) 0.21
Admission NIHSS 16 (10-20) 15 (8-19) 0.47
r-tPA 22 (39.3) 24 (34.8) 0.60
Data presented as median (interquartile range) or number (%).
*Coronary artery disease, heart failure, cardiomyopathy, or valvular disease.
NIHSS indicates National Institutes of Health Stroke Scale; r-tPA, recombinant tissue-type plasminogen activator.

Stroke time intervals, imaging characteristics and outcomes are shown in Table 2. There were no differences in the time from arrival at the IR suite to groin puncture between MAC and GA groups (median [IQR], 9 [6 to 17] vs. 11 [8 to 15] min, respectively; P=0.61). Other stroke time intervals, including door to groin puncture, groin puncture to first pass, groin puncture to recanalization, door to recanalization, and last known normal to recanalization, as well as site of occlusion and complication rates, were also similar between groups. Four patients in the GA group and 9 patients in the MAC group had unknown stroke onset times; however, based on favorable perfusion studies those patients qualified for MT. Only 1 patient with an unknown stroke onset time did not achieve an mTICI rating ≥2b.

TABLE 2 - Time Intervals, Imaging, Stroke Location, and Outcomes
General Anesthesia Monitored Anesthesia Care
N=56 N=69 P
Center workflow times
 Door to groin puncture (min) 151 (99-184) 123 (103-155) 0.16
 IR suite to groin puncture (min) 11 (8-15) 9 (6-17) 0.61
 Groin puncture to first pass 28 (18-47) 28 (19-42) 0.88
  Successful, n (%) 51 (91.1) 62 (89.8) 0.41
 Groin puncture to recanalization (mTICI≥2b) 43 (28-68) 41 (29-58) 0.85
  Successful, n (%) 35 (62.5) 56 (81.1) 0.02
 Door to recanalization (mTICI≥2b) 197 (136-243) 172 (144-201) 0.09
  Successful, n (%) 35 (62.5) 56 (81.1) 0.02
Stroke onset to workflow times in minutes
 Stroke onset to groin puncture (min) 291 (208-677) 282 (164-584) 0.36
 Stroke onset to recanalization—mTICI≥2b (min) 340 (255-827) 353 (212-636) 0.44
Imaging characteristics
 ASPECTS 9 (7-10) 10 (8-10) 0.33
 Penumbra (mL) 103 (68-153) 129 (72-159) 0.67
 Infarct volume (mL) 6 (0-22) 0 (0-20) 0.43
Site of occlusion
 Left circulation 26 (46.4) 41 (59.4) 0.15
 Extracranial ICA 7 (12.5) 15 (21.7) 0.26
 Intracranial ICA/terminus 15 (17.8) 14 (20.2) 0.39
 Tandem occlusion 2 (3.6) 2 (2.9) 0.83
 M1-3 middle cerebral artery 32 (57.1) 38 (55.0) 0.82
Complications
 Symptomatic edema 11 (19.6) 7 (10.1) 0.13
 Craniectomy 3 (5.4) 3 (4.3) 0.79
 Symptomatic hemorrhagic transformation 9 (16.1) 9 (13.0) 0.63
Modified Rankin scale
 Admission mRS 0 (0-1) 0 (0-1) 0.95
 Admission mRS >2 9 (16.1) 5 (8.6) 0.12
 90-d mRS 4 (2-5) 3 (2-5) 0.27
 90-d mRS 0-2 17 (30.4) 31 (44.9) 0.09
 90-d mRS 0-3 26 (46.4) 38 (55.1) 0.34
Mortality
 7-d mortality 9 (16.1) 4 (5.7) 0.06
 90-d mortality 14 (25.0) 13 (18.8) 0.41
Data presented as median (interquartile range) or number (%).
ASPECTS indicates Alberta stroke program early computed tomography score; ICA, internal carotid artery; IR, interventional radiology; mRS, modified Rankin score; mTICI, modified thrombolysis in cerebral infarction.

Significantly fewer patients having GA had successful recanalization compared to those having MAC (62.5 vs. 81.1%, respectively; P<0.02). There were no differences in patient disposition between groups; in the GA and MAC groups, respectively, 25.0% versus 17.3% of patients died during hospitalization or were discharged to a hospice, 26.8% versus 30.4% were discharged to home, and 48.2% versus 52.2% were discharged to a skilled nursing/rehabilitation facility (P=0.58). There was also no difference in 7-day mortality between GA (9 [16.1%] vs. MAC 4 [5.7%]; P=0.06) groups or in 90-day mortality between GA (14 [25.0%] vs. MAC 13 [18.8%]; P=0.41) (Table 2). The 90-day mRS (Fig. 1, Table 2) was similar between groups (P=0.26). There were no significant differences with respect to good functional outcomes (mRS 0 to 2) between GA and MAC (30.4% vs. 44.9%, respectively; P=0.09).

F1
FIGURE 1:
Modified Rankin Scale scores at 3 months in patients receiving either general anesthesia or sedation. The percentage of patients with each outcome (0 to 6) in each group is shown relative to the X axis, and the number of patients with each outcome (0 to 6) is included within the horizontal bars for each group.

Anesthesia

Induction of GA in the IR suite was accomplished with intravenous propofol (1.0 to 2.0 mg/kg), fentanyl (25 to 100 mcg), and intubation was facilitated with succinylcholine or rocuronium for neuromuscular blockade. Anesthesia was maintained with sevoflurane 0.5 to 1.0 MAC (N=53) or propofol infusion 50 to 100 mcg/kg/min (N=3), with supplemental fentanyl as indicated. Twelve patients in the MAC group received fentanyl (median, IQR dose: 75, 50 to 100 mcg) and midazolam (median, IQR dose: 2.0, 1.0 to 2.0 mg). Thirty-six patients in the MAC group received propofol sedation (median, IQR dose: 50, 30 to 75 mcg/kg/h) and 19 patients were administered dexmedetomidine (median, IQR dose: 0.4, 0.4 to 0.7 mcg/kg/min). Twenty-seven (50%) of the patients sedated with propofol or dexmedetomidine received supplemental doses of fentanyl (median, IQR dose: 50, 50 to 100 mcg). The 2 patients that crossed over to GA had sevoflurane as their primary anesthetic.

BP

Median (IQR) baseline MAP in the MAC (109, 94 to 120 mm Hg) and GA (110, 102 to 123 mm Hg) groups was similar (P=0.16). Invasive radial arterial pressure was monitored in 21 (30.4%) and 31 (44.6%) patients in the MAC and GA groups, respectively (P=0.1). Despite institutional target guidelines for BP management during MT, the EPIC anesthesia data record showed significant SBP differences between groups. Overall, 17 (24.6%) patients in the MAC group and 30 (53.5%) in the GA group had SBP outside the target range of 140 to 180 mm Hg (P<0.005). A detailed review of these data identified 4 patients in the MAC group and 2 in the GA group with SBP >180 mm Hg after induction of anesthesia (no significant difference), 8 patients in the MAC group and 11 in the GA group with any MAP <60 mm Hg (P=0.21), and 9 patients in the MAC group and 28 in the GA groups with any MAP <70 mm Hg (P<0.001). Furthermore, of those patients experiencing low BP, median (interquartile range) duration of MAP <70 mm Hg was 10 (5 to 15) and 20 (10 to 36) min in the MAC and GA groups, respectively (P<0.001).

Table 3 shows the univariate analysis of the entire cohort for the dichotomous variables of good (mRS 0 to 2) 90-day outcome (n=48, 38.4%) compared with poor (mRS 3 to 6) 90-day outcome (n=77, 61.6%). There was no significant association of baseline MAP (median [IQR], 107 [99 to 119] vs. 110 [97 to 123]; P=0.69), incidence of any MAP <70 mm Hg (P=0.10) or incidence of MAP <70 mm Hg for 10 minutes or more (P=0.08) with outcomes. Other univariate parameters (prestroke disability, admission NIHSS, ASPECT score, and mTICI <2b) were associated with worse 90-day outcome (P<0.05). A dichotomous multivariate logistic regression analysis was performed with age, prestroke disability, admission NIHSS, ASPECT scores, and mTICI <2b as covariates, and the other univariate factors with a P-value ≤0.1 (gender, anesthesia, MAP <70 mm Hg, or MAP <70 mm Hg >10 min) separately as individual factors into the multivariate analysis (Table 4). That analysis revealed no association of gender, anesthesia (GA vs. MAC) or BP decreases or duration (<70 mm Hg for >10 min) with good versus poor outcome, while the other covariates (age, prestroke disability, admission NIHSS, ASPECT scores, and mTICI <2b) retained significance on multivariate testing (P<0.05).

TABLE 3 - Univariate Analysis for Good (mRS 0 to 2) and Poor Functional (mRS 3 to 6) 90-Day Outcomes
mRS 0-2 mRS 3-6
(N=48) (N=77) P
Patient parameters
 Age (y) 65 (55-71) 77 (59-79) 0.07
 Sex (female) 17 (35.4%) 39 (50.6%) 0.10
 Race 0.20
  Black or African American 21 (43.8%) 44 (57.1%)
  White 27 (56.2%) 32 (41.6%)
  White Hispanic 0 1 (1.3%)
  Asian 0 0
 Smoking 16 (33.3%) 18 (23.4%) 0.30
Area of deprivation index percentile 72 (49-88) 74 (50-92) 0.56
 Hypertension 36 (75.0%) 59 (76.6%) 0.83
 Chronic heart disease* 14 (29.1%) 24 (31.2%) 0.67
 Atrial fibrillation 14 (29.1%) 26 (33.7%) 0.69
 Diabetes 14 (29.1%) 32 (69.6%) 0.19
 Baseline mRS 0 (0-0) 1 (0-2) <0.01
Anesthetic-related parameters
 General 18 (35.4%) 38 (50.6%) 0.10
 ETCO2 <35 mm Hg 6 (12.5%) 13 (16.9%) 0.61
 MAP <60 mm Hg 5 (10.4%) 14 (18.2%) 0.31
 MAP <70 mm Hg 10 (20.8%) 27 (35.0%) 0.09
 MAP <70 mm Hg duration <10 min 6 (12.5%) 23 (29.9%) 0.03
 MAP <70 mm Hg duration (min) 22 (9-30) 15 (5-25) 0.08
Stroke-related parameters
 NIHSS on admission 13 (8-17) 17 (12-21) <0.01
 ASPECTS 10 (8-10) 10 (7-10) 0.02
 r-tPA 21 (43.7%) 25 (32.4%) 0.25
 Stroke onset to recanalization—mTICI≥2b (min) 283 (223-572) 408 (226-784) 0.14
 mTICI≥2b 40 (83.3%) 51 (66.2%) 0.04
 Symptomatic hemorrhagic transformation 4 (8.3%) 14 (26.5%) 0.19
Data presented as median (interquartile range) or number (%).
*Coronary artery disease, heart failure, cardiomyopathy, or valvular disease.
ASPECTS indicates Alberta stroke program early computed tomography score; MAP, mean arterial pressure; mRS, modified Rankin scale; mTICI, modified thrombolysis in cerebral infarction; NIHSS, National Institutes of Health Stroke Scale; r-tPA, recombinant tissue-type plasminogen activator.

TABLE 4 - Multivariate Logistic Regression Model for Good (mRS 0 to 2) and Poor Functional (mRS 3 to 6) 90-Day Outcomes
Variables Adjusted Odds Ratio (95% Confidence Interval) P
Age 1.06 (1.01-1.10) 0.01
Baseline mRS 3.74 (1.89-7.40) <0.01
Admission NIHSS 1.10 (1.02-1.19) 0.02
Baseline ASPECT score 0.53 (0.39-0.81) <0.01
Stroke onset to recanalization—mTICI ≥2b (No) 0.29 (0.09-0.92) 0.03
Sex (female)* 0.77 (0.30-1.96) 0.58
Anesthesia (general)* 1.77 (0.68-4.64) 0.24
MAP <70 mm Hg* 0.72 (0.09-2.28) 0.57
MAP <70 mm Hg for >10 min* 0.28 (0.06-1.24) 0.09
*Variables with P-value ≤0.1 in the univariate analysis that were entered individually into a multivariate logistic regression model with the covariates of age, prestroke disability, admission NIHSS, ASPECT score, and mTICI <2b. Confidence intervals that cross over 1.0 and have a P-value >0.05 had a nonsignificant association. If the adjusted odds ratio was above 1.0 and the confidence interval is entirely above 1.0, then an increase in the variable was associated with an increase in the odds of a poor outcome. If the adjusted odds ratio was below 1.0 and the confidence interval entirely below 1.0, then a lower variable value increased the odds of a poor outcome.
ASPECTS indicates Alberta stroke program early computed tomography score; MAP, mean arterial pressure; mRS, modified Rankin scale; mTICI, modified thrombolysis in cerebral infarction; NIHSS, National Institutes of Health Stroke Scale; r-tPA, recombinant tissue-type plasminogen activator.

With respect to ventilation management, ETCO2 measurement via nasal cannula in the MAC patients was not accurate and used only as respiratory rate indicator. Fifteen (26.8%) patients in the GA group had ETCO2 <35 mm Hg for >5 minutes; median (IQR) ETCO2 was 32 (29 to 34)  mm Hg between postinduction and recanalization/end of the procedure.

DISCUSSION

This evaluation reports a single-center cohort of 125 consecutive adult AIS patients presenting for MT at a university associated comprehensive certified stroke center. Initial reports of the effects of GA for endovascular thrombectomy reported worse outcomes compared to MAC techniques.6–9 However, those results could be secondary to selection bias in anesthetic choice, differences in baseline NIHSS scores, and other critical factor differences between the groups.6,7,26,27 Recent RCTs comparing GA and MAC have not provided definitive conclusions for the superiority of one anesthetic technique over another.10–16 Further data are needed because indications for MT are expanding up to 24 hours from AIS onset based on perfusion imaging, patient management is improving, and there are differences in real-world patient populations (socioeconomic and geographic) compared with those included in controlled trials.

In this retrospective cohort, we found no differences between GA and MAC in clinically significant outcomes (stroke onset to recanalization, disposition, mortality, or neurological outcomes at discharge and 90-d). Like recent trials, the NIHSS score in the GA and MAC groups was similar in our study.12,14–17,28 However, our 90-day outcomes are different to those in the SIESTA15 and GOLIATH16 trials and to the aggregated data from the SIESTA,15 GOLIATH,16 AnStroke,14 and CANVAS pilot trials which indicated that GA is superior to MAC for improved 90-day outcomes (mRS 0 to 2).11,14–16,28

Consistent with previous studies, the multivariate analysis of our patient cohort identified age, baseline NIHSS, ASPECTS, and recanalization as predictive of functional outcomes after AIS.6,7,29–31 BP has been shown to be another modifiable factor influencing functional recovery after MT for AIS independent of anesthetic choice.29–34 This association is most prevalent in retrospective cohort studies showing that every 10 mm Hg decrease in MAP from baseline,29,31 MAP <70 mm Hg,29 MAP <60 mm Hg (57.3% incidence),30 or a 40% decrease in MAP from baseline (63.8% incidence)32 was associated with worse functional outcomes. MAP decreases of 20% or more are more common during GA,12,17,28,33 but the RCTs of GOLIATH, SIESTA, and AnStroke14,34,35 found no association between MAP decreases and 90-day outcomes. However, a multivariate analysis of aggregated hemodynamic data from GOLIATH, SIESTA, and AnStroke, (n=365)33 showed that MAP <70 mm Hg (adjusted odds ratio: 1.81, 95% confidence interval: 1.1-2.9; P=0.02) and duration of MAP <70 mm Hg (adjusted odds ratio: 1.30, 95% confidence interval: 1.03-1.65; P=0.03) was associated with higher 90-day mRS scores, indicating that smaller studies are underpowered to detect an association of lower MAPs with poor outcomes.

The BP target during MT at our institution is SBP 140 to 180 mm Hg, and we also observed greater hemodynamic instability with GA as previously reported.12,14,17,28,33,35 Based on recent studies implicating low BP (MAP <60 and <70 mm Hg) with worse 90-day outcomes, we also evaluated our cohort with regard to those low MAP thresholds in addition to SBP.30,33 We observed a 15.2% incidence (GA, n=12; MAC, n=7) of MAP <60 mm Hg compared with the 56% incidence reported by Fandler-Höfler et al.30 We also observed a 29.6% incidence of any MAP <70 mm Hg which is lower than that reported in previous retrospective studies but similar to GOLIATH (25.7%)35 and AnStroke (26.7%).14 While we found differences in low MAP between GA and MAC groups, the MAP perturbations were not associated with worse 90-day outcomes (mRS 3 to 6) in the binary multivariate analysis.

Patient populations for MT in clinical practice are known to vary significantly from those in RCTs based on study inclusion/exclusion criteria.18,19 In our cohort we found similarities and differences which may impact the generalizability of the results. Compared with data aggregated from RCTs, we observed a lower rate of recanalization with GA (62.5% vs. 86.2%), a similar rate of recanalization with MAC (81.1% vs. 74.6%), and similar rates of favorable (mRS 0 to 2) outcomes (38% vs. 43%).11 The recanalization findings could represent selection bias for GA for technically challenging thrombectomies or random variability as observed in the GOLIATH study where recanalization with GA was 76.9% compared with 60.3% with MAC.16 For example, distal lesions are considered more technically challenging and at higher risk for hemorrhagic conversion and the number of occlusions at M2 or M3 were higher in this study (24.8%) compared with 10.1% in the combined SIESTA, GOLIATH, and AnStroke data.33 The majority of the distal occlusions in our study were in the GA group (32%) which represents possible selection bias for GA to minimize inadvertent movement during MT for distal middle cerebral artery occlusions.

While patient medical characteristics, stroke severity scores, use of modern stent retriever/aspiration devices, outcomes, and control of BP perturbations in our study cohort were similar to controlled trials, there were marked differences in other aspects. Our use of r-TPA, a favorable outcome predictor in combination with thrombectomy,36 was 36.5% compared with 70.7% in the aggregated data from SIESTA, GOLIATH, and AnStroke.33 This difference is based primarily on time interval from symptom onset. Our cohort includes 33 patients with onset to door times >8 hours (range: 426 to 1402 min) with an additional 13 unknown times from unwitnessed or “wake-up” strokes treated within a presumptive 24-hour window. In contrast, the onset time for inclusion in AnStroke was <8 hours14 and less in the other trials.12,15,16 Of note, GA did not contribute to these differences; the median IR suite arrival to groin puncture time of 11 minutes for GA patients in our study was 12 minutes faster than reported in the RCTs,33 and similar to those reported by Ren et al12 (also 11 min).

Previous studies have not expanded on the reasons for GA taking longer to implement than MAC.14–16 In our center, the anesthesiologist responsible for coordinating resources is informed immediately a decision is made to perform MT. This allows for review of the patient in EPIC and preparation for the procedure. In addition to having the IR suite prepared to receive a patient, IV infusions, anesthesia circuit and oxygen cannula have extensions to facilitate minimal movement of equipment at any time during the procedure. The teamwork within IR suite also represents learned trauma center efficiency where the patient record is opened before the patient’s arrival, monitors tested to ensure the EPIC gateway is functioning, the transport team moves and performs initial positioning of the patient while the IR nurse focuses on patient identification processes (with a brief pause of all activity during the time out), and the IR technician and proceduralist apply betadine to the groin and sterile drapes and perform groin puncture at the same time the anesthesia team is initiating anesthesia induction. This process is further simplified by the use of transport monitor modules that are fully compatible with the IR monitor, with the monitoring transition requiring insertion of the transport module into the IR monitor dock without exchanging cables or monitoring devices.

An important difference between a pragmatic clinical patient cohort and patients recruited into controlled trials is the inclusion of all patients. Our study included 14 patients (9.3%) with a baseline mRS of 3 or 4, and these patients would have been excluded from most RCTs. There are also discretionary exclusions to randomization due to agitation or airway/anesthesia concerns in RCTs.12,14,15 These criteria are understandable and a source of bias toward GA in clinical practice as indicated by our low MAC to GA conversion rate (1.6%) compared with higher conversion rates in other studies (6% to 15%).12,14–16

Another factor that may differentiate patients and may impact outcome is related to social determinants of health. Review of administrative datasets show lower rates of MT in uninsured patients, and black compared with white patients.21,22 In addition, a recent evaluation indicated that low socioeconomic status was an unadjusted risk factor for worse 90-day MT outcomes (mRS 3 to 6).23 University of Florida Health Jacksonville has a unique role as a comprehensive certified stroke center serving a predominantly disadvantaged population, as witnessed by the area of deprivation index of our study population (Table 2). The area of deprivation index was developed by Singh and Siahpush37 and updated by Kind et al38 and Hu et al.39 It combines 17 measures of income, employment, education, and housing collected in the 2018 American Community Survey and exists as an easy-to-use online map of deprivation based on the aggregate information validated to census block groups/neighborhoods of 1500 people based on address.25,40 The area of deprivation index has significant correlation with the severity of diabetes mellitus, coronary heart disease, stroke, colorectal cancer, as well as nonadherence to medications.37,38 In particular, and relevant to our population, is the impact of low socioeconomic status on increased mortality after stroke.24 Despite optimization of care pathways, the impact of socioeconomic status on conventional risk factors and rehabilitation resources may impact good outcomes in this population compared with other cohorts.11,12 Median area of deprivation index or quartile distribution was not different between GA and MAC groups in our study or when comparing good functional outcome to poor functional outcome. The availability of high-quality MT care may be able to ameliorate the impact of low socioeconomic status on increased mortality after stroke. However, these findings must be interpreted with caution as, like for our MAP data, this study may be underpowered to predict worse outcomes.

This study has some limitations. Its’ small sample size and single-center, retrospective design has the potential to introduce selection bias. As noted above, the study may be underpowered to detect differences between GA and MAC on the impact of socioeconomic status and MAP on 90-day outcomes. The findings may also not be generalizable to centers that use different approaches to anesthesia, have limited access to on demand advanced anesthesia care, and with differences in neurointerventional treatment.

CONCLUSIONS

This evaluation reflects a broader practice than RCTs, representing a patient population with extended stroke intervals from onset to treatment and low socioeconomic status that may impact outcomes. These differences from controlled trials underscore the rapid progression of stroke therapy in recent years. SIESTA,16 GOLIATH,15 and AnStroke14 enrolled patients between 2014 and 2017, Ren et al12 between 2017 and 2018, and our study between 2017 and 2020. Despite expanded intervention times presenting challenges of comparability with other studies, we found no difference in primary MT outcomes (mortality and mRS at 90-d) between GA and MAC. The incidence of MAP below 60 or 70 mm Hg in this evaluation is underpowered to predict outcomes, yet the 29.6% incidence of a MAP <70 mm Hg indicates further improvement can be attained in this modifiable factor. We could not determine if socioeconomic status (as indicted by the area of deprivation index) impacted outcomes in our patients, and this is an area that requires further evaluation in a larger cohort with greater socioeconomic variability.

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Keywords:

acute ischemic stroke; anesthesia; general; conscious sedation; health care disparities; mechanical thrombolysis; socioeconomic factors; area of deprivation index

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