Marshall, Randolph S.

Importance Cerebral hemodynamic impairment in patients with asymptomatic internal carotid artery (ICA) stenosis is associated with reduced cognition. It is uncertain whether revascularization might be an effective treatment for cognitive impairment in these patients. Objective To test whether any cognitive benefit from revascularization of high-grade, asymptomatic ICA stenosis varies based on the degree of baseline cerebral hemodynamic impairment. Design, Setting, and Participants This substudy was conducted within a multicenter phase 3 randomized clinical trial. Adults (aged 35-86 years) without dementia with eighth-grade education or higher and unilateral asymptomatic ICA stenosis greater than or equal to 70% were enrolled from January 2018 to July 2024 at 61 sites in North America (last follow-up in July 2025). Of 607 participants screened from 2485 in CREST-2, 392 were enrolled. Magnetic resonance or computed tomographic perfusion imaging tested for baseline hemodynamic impairment defined by delayed time-to-peak (TTP) arrival of intravenous contrast in the hemisphere ipsilateral minus contralateral to the stenotic artery. Intervention Carotid revascularization (endarterectomy or stenting) plus intensive medical management (IMM) vs IMM alone. Main Outcomes and Measures The primary outcome was the difference in composite cognitive z score over 1 year based on 5 cognitive tests. The primary analysis tested for an interaction between treatment group (revascularization vs IMM alone) and degree of baseline hemodynamic impairment among those with reduced baseline cognition (cognitive z score ≤−1.0 SD). Results Of 392 participants enrolled (mean age, 71 years; 125 [32%] females), 61 were excluded for missing baseline imaging and 40 for missing cognitive examinations or other covariates, leaving 291 with complete data. Fifty-one had reduced cognition at baseline (25 in the revascularization group and 26 in the IMM alone group). TTP ranged from no interhemispheric TTP delay to a more-than-2-second delay. Mean (SD) cognitive z scores were −1.36 (0.51) at baseline and −1.17 (0.47) at 1 year in the revascularization group and −1.34 (0.83) at baseline and −1.01 (0.97) at 1 year in the IMM alone group. The primary analysis showed no difference in cognition by treatment group over 1 year, adjusting for treatment group × hemodynamic status interaction and other covariates (adjusted difference in cognitive z score, −0.15 SD [95% CI, −0.54 to 0.24]). The interaction was not significant (β estimate = 0.018 [95% CI, −0.025 to 0.061]; P = .40). Conclusions and Relevance In this substudy of a randomized clinical trial, there was no differential effect of revascularization vs IMM alone on cognition over 1 year by cerebral hemodynamic status among those with baseline reduced cognition, suggesting that revascularization does not improve cognitive dysfunction by restoring flow to the brain in chronic asymptomatic carotid stenosis. Trial Registration ClinicalTrials.gov Identifier: NCT03121209

Objectives: Cerebral hemodynamic impairment in patients with asymptomatic high-grade internal carotid artery (ICA) stenosis confers a risk of stroke and cognitive decline, but correlations between degree of stenosis and hemodynamic impairment are derived from small case series only. Using baseline data from 282 participants in the Carotid Revascularization and Medical Management for Asymptomatic Carotid Stenosis – Hemodynamics (CREST-H) study, we hypothesized that degree of stenosis, measured by peak systolic velocity (PSV) and end diastolic velocity (EDV) in the ipsilateral ICA, would correlate with time-to-peak (TTP) delay using MR (n=275) or CT (n=7) perfusion scans, adjusting for demographic and cardiovascular risk variables. Methods: Using a 7-10MHz Doppler probe, ICA PSV and EDV were assessed. Doppler results were adjudicated centrally. Dynamic contrast perfusion imaging was standardized across 61 CREST-H sites, using sequential T2*-weighted time-sequence scanning (e.g. TR=1500, TE=25ms, flip angle=60deg, phase=128, slice thickness=5mm for GE 3T magnet). CTP was acquired with standard clinical protocols. TTP delay was calculated in the ipsilateral versus contralateral MCA/ACA territories using OLEA software. Linear regression used TTP delay as the outcome variable and PSV and EDV as predictor variables, adjusting for covariates.The 282 with complete data for all variables were included in the analysis. Results: Among 392 CREST-H participants, 63% were men, 7% Black, 3% Hispanic, 33% with less than college education. Tables 1a/b show the regression results for PSV and EDV as main predictor variables. PSV and EDV on the index side significantly correlated with TTP delay (p=0.004, p=0.002 respectively). Neither PSV nor EDV on the non-index side correlated with TTP delay (p=0.49, p=0.82). Compared with moderate exercise, vigorous exercise correlated with lower TTP delay in both models (p=0.05. p=0.04). Compared with college graduates, those with HS education had longer TTP delays in both models (p=0.03. p=0.02). Conclusions: In this large cohort of patients with high-grade asymptomatic carotid stenosis, higher flow velocities correlated with greater TTP delays, suggesting an increasing hemodynamic impairment with greater degree of stenosis above 70%. Our findings have implications for management of asymptomatic carotid stenosis which are being tested in the CREST-H and CREST-2 studies. Exercise and education may independently impact cerebral hemodynamics.

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.

Background: Previous reports have established a relationship between asymptomatic high-grade carotid artery stenosis (CAS) and impaired cognition. Different forms of cardiac disease have also been associated with cognitive impairment and dementia. The effect of concurrent high-grade CAS and cardiac disease on cognition is unknown. We hypothesize the presence of comorbid cardiac disease has a synergistic effect on cognitive impairment in patients with asymptomatic CAS. Methods: Patients with ≥80% internal carotid artery stenosis with no history of stroke were recruited from inpatient and outpatient practices at a single, large, comprehensive stroke center. Patients with vs without comorbid cardiac disease (coronary artery disease [CAD], CAD with history of coronary artery bypass graft [CABG] or percutaneous intervention [PCI], heart failure [HF], atrial fibrillation [AF], or valvular disease [aortic or mitral]) were identified. Cognitive assessments were performed using a battery of 14 standardized tests of attention, memory, processing speed, visual construction, language and executive function. Z-scores were generated based on age-specifc norms. Multivariable linear regression was used to compare test-specific Z-scores in patients with vs without cardiac disease controlling for age, sex, years of education and depression. Results: Thirty-three patients with asymptomatic CAS were identified (21 males, age 74+/-10 years, education=16+/-3 years). Twenty-six (79%) had cardiac disease. Patients with comorbid cardiac disease had significantly lower Z-scores across multiple tests of memory compared to patients without cardiac disease (Fig). After adjusting for age, sex, years of education and depression, significant differences persisted in tests of memory in patients with CAD [Hopkins Recognition Memory Test, β= -1.127 (95% CI: -2.234, -0.020), P=0.046], CABG [Hopkins Learning Trial Memory Test, β= -1.441 (95% CI: -2.532, -0.350), P=0.012], and valvular disease [Hopkins Learning Trials Memory Test, β= -1.121 (95% CI: -2.224, -0.018), P=0.047]. Conclusion: Cardiac disease is common among patients with asymptomatic high-grade carotid stenosis and may have a synergistic effect on impairments in memory in a manner not mediated by stroke. Further work is needed to confirm these relationships and their longterm implications on vascular brain health.

Background and Purpose: Studies of carotid artery disease have suggested that high-grade stenosis can affect cognition, even without stroke. The presence and degree of cognitive impairment in such patients have not been reported and compared with a demographically matched population-based cohort. Methods: We studied cognition in 1000 consecutive CREST-2 (Carotid Revascularization and Medical Management for Asymptomatic Carotid Stenosis Trial) patients, a treatment trial for asymptomatic carotid disease. Cognitive assessment was after randomization but before assigned treatment. The cognitive battery was developed in the general population REGARDS Study (Reasons for Geographic and Racial Differences in Stroke), involving Word List Learning Sum, Word List Recall, and Word List fluency for animal names and the letter F. The carotid stenosis patients were >45 years old with ≥70% asymptomatic carotid stenosis and no history of prevalent stroke. The distribution of cognitive performance for the patients was standardized, accounting for age, race, and education using performance from REGARDS, and after further adjustment for hypertension, diabetes, dyslipidemia, and smoking. Using the Wald Test, we tabulated the proportion of Z scores less than the anticipated deviate for the population-based cohort for representative percentiles. Results: There were 786 baseline assessments. Mean age was 70 years, 58% men, and 52% right-sided stenosis. The overall Z score for patients was significantly below expected for higher percentiles ( P <0.0001 for 50th, 75th, and 95th percentiles) and marginally below expected for the 25th percentile ( P =0.015). Lower performance was attributed largely to Word List Recall ( P <0.0001 for all percentiles) and for Word List Learning (50th, 75th, and 95th percentiles below expected, P ≤0.01). The scores for left versus right carotid disease were similar. Conclusions: Baseline cognition of patients with severe carotid stenosis showed below normal cognition compared to the population-based cohort, controlling for demographic and cardiovascular risk factors. This cohort represents the largest group to date to demonstrate that poorer cognition, especially memory, in this disease. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT02089217.

Background: Perfusion weighted imaging on MRI (MRP) and computerized tomography perfusion (CTP) are increasingly required to manage large vessel disease. Computerized algorithms can quantify perfusion data, but the programs are expensive and not widely used outside acute stroke evaluation. We aimed to determine how well human observers can identify asymmetries in cerebral perfusion images compared with an automated computer algorithm. Methods: Ten clinicians experienced in treating carotid artery disease (4 vascular neurologists, 3 neuroradiologists, 1 vascular surgeon, 1 neurosurgeon, 1 interventional radiologist) were given 28 post-processed, color-coded, axial-slice MRP scans from patients in the Carotid Revascularization Endovascular versus Stenting Trial - Hemodynamics (CREST-H) study. All patients had >70%, unilateral, asymptomatic carotid artery stenosis and had varying degrees of time-to-peak (TTP) delay on the side of stenosis, ranging from 0 to 2 secs, quantified by a semi-automated system that computes quantitative perfusion maps, using deconvolution of tissue and arterial signals (Olea, Cambridge, MA). A minimum volume of 10cc was required for a given TTP delay. Clinicians were asked to determine asymmetry (y/n) and side of occlusion for each case. Number of correct responses that matched the computer output were tallied. Results: We averaged correct responses by the 10 clinicians for cases at each increment of TTP delay; (Figure). At TTP delays ≥1.5 seconds, accuracy was ≥80%. At 1.25 sec accuracy fell to 60%, and at ≤ 1 sec, accuracy was ≤50%. For TTP=0 (no asymmetry), accuracy was 71%. Conclusions: Visual impression of hemodynamic asymmetry among experienced clinicians was reasonably accurate for TTP delays ≥1.5 seconds, but declined with more subtle asymmetries. Depending on the clinical impact of TTP delays (for CREST-H: correlation with cognitive decline), experienced clinicians may perform as well as an automated algorithm.

Rationale For patients with asymptomatic high-grade carotid stenosis, clinical investigations have focused on preventing cerebral infarction, yet stenosis that reduces cerebral blood flow may independently impair cognition. Whether revascularization of a hemodynamically significant carotid stenosis can alter the course of cognitive decline has never been investigated in the context of a randomized clinical trial. Hypothesis Among patients randomized in the Carotid Revascularization and Medical Management for Asymptomatic Carotid Stenosis (CREST-2) trials, the magnitude of treatment differences (revascularization versus medical management alone) with regard to cognition will differ between those with flow impairment compared to those without flow impairment. Sample size We will enroll approximately 500 patients from CREST-2, of which we anticipate 100 will have hemodynamic impairment. We estimate 93% power to detect a clinically meaningful treatment difference of 0.5 SD. Methods and design We will use perfusion-weighted magnetic resonance imaging to stratify by hemodynamic status. Linear regression will compare treatment differences, controlling for baseline cognitive status, age, depression, prior cerebral infarcts, silent infarction, white matter hyperintensity volume, and cerebral microbleeds. Study outcomes The primary outcome is change in cognition at one year. Secondary outcomes include silent infarction, change in white matter hyperintensity volume, number of cerebral microbleeds, and cortical thickness over one year. Discussion If cognitive impairment can be shown to be reversible by revascularization, then we can redefine “symptomatic carotid stenosis” to include cognitive impairment and identify a new population of patients likely to benefit from revascularization. Trial Registration US National Institutes of Health (NIH) clinicaltrials.gov NCT03121209