Howard, George

BACKGROUND: Cerebral hemodynamic impairment in patients with asymptomatic high-grade (>70%) internal carotid artery (ICA) stenosis is associated with risk of stroke and cognitive decline, but correlations between the degree of stenosis and hemodynamic impairment are derived from small case series. Using baseline data from 242 participants in the CREST-H study (Carotid Revascularization and Medical Management for Asymptomatic Carotid Stenosis–Hemodynamics), we hypothesized that the degree of stenosis in the ICA would correlate with time-to-peak (TTP) delay in ipsilateral cerebral blood flow using MR/CT perfusion scans, adjusting for demographic and cardiovascular risk variables. METHODS: From all participants, ICAs were insonated using a 7 to 10 MHz probe for peak systolic velocity (PSV) and end diastolic velocity. Dynamic contrast perfusion imaging was standardized across 61 CREST-H sites, using standard sequential T2*-weighted perfusion imaging. CT perfusion used standard clinical protocols. TTP delay was calculated in the ipsilateral versus contralateral hemispheres. In cross-sectional analysis, linear regression was used to model TTP delay as the outcome variable and PSV, end diastolic velocity, and PSV ICA/common carotid artery ratio on the index and nonindex side as primary predictor variables in 6 separate models, adjusting for covariates, followed by automated backward elimination model reduction. RESULTS: Among 392 CREST-H participants, the 242 with complete data for all variables were included in the regression analysis (age, 70±7.6; 62% M). End diastolic velocity on the index side correlated with TTP delay (β=0.003, P =0.005). PSV had a similar correlation but did not reach significance (β=0.001, P =0.099), nor did ICA/common carotid artery ratio (β=0.003, P =0.126). Nonindex side PSV, end diastolic velocity, and ICA/common carotid artery ratio showed no correlation with TTP delay ( P =0.268, P =0.495, P =0.380, respectively). Circle of Willis completeness did not correlate with TTP. CONCLUSIONS: In this large cohort of patients with high-grade asymptomatic carotid stenosis, higher end-diastolic flow velocities correlated with greater TTP delays, supporting a definition of hemodynamically significant stenosis. Our findings have implications for the management of asymptomatic carotid stenosis, which will be tested in the CREST-H study. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT03121209.

The recently published SPACE-2 trial (Stent-Supported Percutaneous Angioplasty of the Carotid Artery Versus Endarterectomy-2) compared 3 treatments to prevent stroke in patients with asymptomatic carotid stenosis ≥70%: (1) carotid endarterectomy plus best medical treatment (BMT), (2) transfemoral carotid artery stenting plus BMT, or (3) BMT alone. Because of low enrollment, the findings of similar safety and efficacy for carotid endarterectomy, carotid artery stenting, or BMT alone were inconclusive. Publication of the CREST (Carotid Revascularization and Medical Management for Asymptomatic Carotid Stenosis Trial)-2 results should provide level A evidence that has been lacking for 2 to 3 decades, to guide treatment of asymptomatic patients with severe carotid stenosis. For symptomatic patients with ≥70% stenosis, no trials are underway to update the degree of benefit reported for carotid endarterectomy by NASCET (North American Carotid Endarterectomy Trial) and ECST (European Carotid Surgery Trial), published in 1991. Subsequently, the use of cigarettes has plummeted, and major improvements in medical treatments and in carotid revascularization have emerged. These advances have coincided with abrupt decline in the clinical end points necessary for treatment comparisons in procedural trials. One of the advances in the invasive management of carotid disease has been transcarotid artery revascularization, already with limited approval by the US Food and Drug Administration. Establishing safety and efficacy of transcarotid artery revascularization compared with carotid endarterectomy, carotid artery stenting, or BMT alone may be challenging because of enrollment, regulatory, and funding barriers to design and complete an adequately powered randomized trial.

Background and Purpose: Despite a higher incidence of stroke and a more adverse cardiovascular risk factor profile in Blacks and Hispanics compared with Whites, carotid artery revascularization is performed less frequently among these subpopulations. We assessed racial differences in high-grade (≥70% diameter-reducing) carotid stenosis. Methods: Consecutive clients in a Nationwide Life Line for-Profit Service to screen for vascular disease, 2005 to 2019 were evaluated in a cross-sectional study. The prevalence of high-grade stenosis, defined by a carotid ultrasound peak systolic velocity of ≥230 cm/s, was assessed. Participants self-identified as White, Black, Hispanic, Asian, Native American, or other. Race/ethnic differences were assessed using Poisson regression. The number of individuals in the United States with high-grade stenosis was estimated by applying prevalence estimates to 2015 US Census population estimates. Results: The prevalence of high-grade carotid stenosis was estimated in 6 130 481 individuals. The prevalence of high-grade stenosis was higher with increasing age in all race-sex strata. Generally, Blacks and Hispanics had a lower prevalence of high-grade stenosis compared with Whites, while Native Americans had a higher prevalence. For example, for men aged 55 to 65, the relative risk of stenosis compared with Whites was 0.40 (95% CI, 0.29–0.55) and 0.61 (95% CI, 0.46–0.81) for Blacks and Hispanics, respectively; and 1.53 (95% CI, 1.12–2.10) for Native Americans. When these prevalence estimates were applied to the Census estimates of the US population, an estimated 327 721 individuals have high-grade stenosis, of whom 7% are Black, 7% Hispanic, and 43% women. Conclusions: Despite their having a more adverse cardiovascular risk profile, there was a lower prevalence of high-grade carotid artery stenosis for both the Black and Hispanic relative to the White clients. This lower prevalence of high-grade stenosis is a potential contributor to the lower use of carotid revascularization procedures in these minority populations.

Background and Purpose: CREST (Carotid Revascularization Endarterectomy Versus Stenting Trial) reported a higher periprocedural risk for any stroke, death, or myocardial infarction for women randomized to carotid artery stenting (CAS) compared with women randomized to carotid endarterectomy (CEA). No difference in risk by treatment was detected for women relative to men in the 4-year primary outcome. We aimed to conduct a pooled analysis among symptomatic patients in large randomized trials to provide more precise estimates of sex differences in the CAS-to-CEA risk for any stroke or death during the 120-day periprocedural period and ipsilateral stroke thereafter. Methods: Data from the Carotid Stenosis Trialists’ Collaboration included outcomes from symptomatic patients in EVA-3S (Endarterectomy Versus Angioplasty in Patients With Symptomatic Severe Carotid Stenosis), SPACE (Stent-Protected Angioplasty Versus Carotid Endarterectomy in Symptomatic Patients), ICSS (International Carotid Stenting Study), and CREST. The primary outcome was any stroke or death within 120 days after randomization and ipsilateral stroke thereafter. Event rates and relative risks were estimated using Poisson regression; effect modification by sex was assessed with a sex-by-treatment-by-trial interaction term, with significant interaction defined a priori as P ≤0.10. Results: Over a median 2.7 years of follow-up, 433 outcomes occurred in 3317 men and 1437 women. The CAS-to-CEA relative risk of the primary outcome was significantly lower for women compared with men in 1 trial, nominally lower in another, and nominally higher in the other two. The sex-by-treatment-by-trial interaction term was significant ( P =0.065), indicating heterogeneity among trials. Contributors to this heterogeneity are primarily differences in periprocedural period. When the trials are nevertheless pooled, there were no significant sex differences in risk in any follow-up period. Conclusions: There were significant differences between trials in the magnitude of sex differences in treatment effect (CAS-to-CEA relative risk), indicating pooling data from these trials to estimate sex differences might not be valid. Whether sex is acting as an effect modifier of the CAS-to-CEA treatment effect in symptomatic patients remains uncertain. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT00190398 (EVA-3S) and NCT00004732 (CREST). URL: https://www.isrctn.com ; Unique identifier: ISRCTN57874028 (SPACE) and ISRCTN25337470 (ICSS).

Background and Purpose— We investigated whether procedural stroke or death risk of carotid artery stenting (CAS) compared with carotid endarterectomy (CEA) is different in patients with and without history of coronary heart disease (CHD) and whether the treatment-specific impact of age differs. Methods— We combined individual patient data of 4754 patients with symptomatic carotid stenosis from 4 randomized trials (EVA-3S [Endarterectomy Versus Angioplasty in Patients With Symptomatic Severe Carotid Stenosis], SPACE [Stent-Protected Angioplasty Versus Carotid Endarterectomy], ICSS [International Carotid Stenting Study], and CREST [Carotid Revascularization Endarterectomy Versus Stenting Trial]). Procedural risk was defined as any stroke or death ≤30 days after treatment. We compared procedural risk between both treatments with Cox regression analysis, stratified by history of CHD and age (<70, 70–74, ≥75 years). History of CHD included myocardial infarction, angina, or coronary revascularization. Results— One thousand two hundred ninety-three (28%) patients had history of CHD. Procedural stroke or death risk was higher in patients with history of CHD. Procedural risk in patients treated with CAS compared with CEA was consistent in patients with history of CHD (8.3% versus 4.6%; hazard ratio [HR], 1.96; 95% CI, 0.67–5.73) and in those without (6.9% versus 3.6%; HR, 1.93; 95% CI, 1.40–2.65; P interaction =0.89). In patients with history of CHD, procedural risk was significantly higher after CAS compared with CEA in patients aged ≥75 (CAS-to-CEA HR, 2.78; 95% CI, 1.32–5.85), but not in patients aged <70 (HR, 1.71; 95% CI, 0.79–3.71) and 70 to 74 years (HR, 1.09; 95% CI, 0.45–2.65). In contrast, in patients without history of CHD, procedural risk after CAS was higher in patients aged 70 to 74 (HR, 3.62; 95% CI, 1.80–7.29) and ≥75 years (HR, 2.64; 95% CI, 1.52–4.59), but equal in patients aged <70 years (HR, 1.05; 95% CI, 0.63–1.73; 3-way P interaction =0.09). Conclusions— History of CHD does not modify procedural stroke or death risk of CAS compared with CEA. CAS might be as safe as CEA in patients with history of CHD aged <75 years, whereas for patients without history of CHD, risk after CAS compared with CEA was only equal in those aged <70 years.

Background: The Carotid Revascularization Endarterectomy versus Stenting Trial (CREST) previously reported increased mortality in patients who sustained a periprocedural stroke or cardiac event (myocardial infarction [MI] or biomarker only) in follow-up to 4 years. We now extend these observations to 10 years. Methods and Results: CREST is a randomized controlled trial designed to compare the outcomes of carotid stenting versus carotid endarterectomy. Proportional hazards models were used to assess the association between mortality and periprocedural stroke, MI, or biomarker-only events. For 10-year follow-up, patients with periprocedural stroke were at 1.74× the risk of death compared with those without stroke (adjusted hazard ratio [HR]=1.74; 95% CI, 1.21–2.50; P <0.003). This increased risk was driven by increased early (between 0 and 90 days) mortality (adjusted HR=14.41; 95% CI, 5.33–38.94; P <0.0001), with no significant increase in late (between 91 days and 10 years) mortality (adjusted HR=1.40; 95% CI, 0.93–2.10; P =0.11). Patients with a protocol MI were at 3.61× increased risk of death compared with those without MI (adjusted HR=3.61; 95% CI, 2.28–5.73; P <0.0001), with an increased hazard both early (adjusted HR=8.20; 95% CI, 1.86–36.2; P =0.006) and late (adjusted HR=3.40; 95% CI, 2.09–5.53; P <0.0001). Patients with a biomarker-only event were at 2.04× increased risk overall (adjusted HR=2.04; 95% CI, 1.09–3.84; P =0.03) than those without MI, with an increased early hazard (adjusted HR=8.44; 95% CI, 1.09–65.5; P =0.04) and a suggestive but nonsignificant association toward higher 91-day to 10-year risk (1.88; 95% CI, 0.97–3.64; P =0.062) contributing to the increased risk. Conclusions: In the CREST trial, patients with periprocedural events demonstrate a substantial increase in future mortality to 10 years. For stroke, this risk is largely confined to an early time frame while periprocedural MI or biomarker-only events confer a continuous increased mortality for 10 years. Strategies to reduce periprocedural events and to optimize the evaluation and management of patients with cardiac events should be considered in efforts to reduce not only early but also long-term mortality. Clinical Trial Registration: URL: https://www.clinicaltrials.gov . Unique identifier: NCT00004732.

Background and Purpose— Stenting for symptomatic carotid stenosis (carotid artery stenting [CAS]) carries a higher risk of procedural stroke or death than carotid endarterectomy (CEA). It is unclear whether this extra risk is present both on the day of procedure and within 1 to 30 days thereafter and whether clinical risk factors differ between these periods. Methods— We analyzed the risk of stroke or death occurring on the day of procedure (immediate procedural events) and within 1 to 30 days thereafter (delayed procedural events) in 4597 individual patients with symptomatic carotid stenosis who underwent CAS (n=2326) or CEA (n=2271) in 4 randomized trials. Results— Compared with CEA, patients treated with CAS were at greater risk for immediate procedural events (110 versus 42; 4.7% versus 1.9%; odds ratio, 2.6; 95% CI, 1.9–3.8) but not for delayed procedural events (59 versus 46; 2.5% versus 2.0%; odds ratio, 1.3; 95% CI, 0.9–1.9; interaction P =0.006). In patients treated with CAS, age increased the risk for both immediate and delayed events while qualifying event severity only increased the risk of delayed events. In patients treated with CEA, we found no risk factors for immediate events while a higher level of disability at baseline and known history of hypertension were associated with delayed procedural events. Conclusions— The increased procedural stroke or death risk associated with CAS compared with CEA was caused by an excess of events occurring on the day of procedure. This finding demonstrates the need to enhance the procedural safety of CAS by technical improvements of the procedure and increased operator skill. Higher age increased the risk for both immediate and delayed procedural events in CAS, mechanisms of which remain to be elucidated. Clinical Trial Registration— URL: https://clinicaltrials.gov . Unique identifier: NCT00190398. URL: http://www.isrctn.com . Unique identifier: ISRCTN57874028. URL: http://www.isrctn.com . Unique identifier: ISRCTN25337470. URL: https://clinicaltrials.gov . Unique identifier: NCT00004732.