Carotid endarterectomy (CEA) vs standard medical therapy alone for asymptomatic severe carotid stenosis has a statistically significant, though small, protective effect from ipsilateral stroke, according to findings published in the Journal of Vascular Surgery.
Investigators aimed to compare CEA plus standard medical therapy versus medical therapy alone for prevention of ipsilateral stroke in adult patients with severe carotid stenosis. The primary endpoint was acute ipsilateral ischemic stroke.
They conducted a retrospective observational, data-only (causal inference) cohort study that included 3824 patients aged at least 18 years (mean age, 73.7 years ) who had severe (70% to 99%) carotid stenosis (no neurological symptoms within 6 months) with no prior ipsilateral carotid artery intervention. Using electronic medical-record data from January 2008 through December 2017, the investigators at Kaiser Permanente Northern California integrated health care delivery system applied causal inference methods to compare event-free survival over 8 years between patients with CEA within 12 months from cohort entry vs standard medical therapy alone.
Among patients with bilateral severe disease, 1 side was chosen at random, and only 1 severe stenosis per patient was included.
Among the included patients (57.9% men; 73% non-Hispanic White patients; 12.3% active smokers; 50.1% former smokers), 1467 patients received CEA (86% in the first 12 months), and 2357 received standard therapy alone. Median time to surgery was 2 months (IQR, 1-5 months).
During follow-up (median 68 months), 1760 patients died, 445 were lost to follow-up, and 158 (4.1%) experienced ipsilateral ischemic stroke. Overall, 1461 patients survived without experiencing stroke through the end of the study.
For each year of follow-up, compared with patients who received standard therapy alone, cumulative risk differences showed a protective effect from ipsilateral stroke over time starting in year 2 (risk difference [RD], 1.1%; 95% CI, 0.5%-1.6%; P <.001) in patients that received CEA, continuing to year 8 (RD, 2.6%; 95% CI, 0.3%-4.8%; P =.03).
Significant survival advantages were demonstrated via cumulative risk differences in the CEA group vs standard therapy alone group in the composite endpoint of stroke and death in year 2 (RD, 6.7%; 95% CI, 4.7%-8.7%) continuing to year 8 (RD, 13.7%; 95% CI, 8.4%-18.9%).
Study limitations include the disease severity being assigned by imaging reports, and assessment of documented transient ischemic stroke in the Kaiser electronic health records is unreliable.
“In this retrospective study utilizing techniques to mimic a clinical trial, carotid endarterectomy was found to be protective of stroke in patients with asymptomatic stenosis compared with medical therapy alone,” the investigators wrote. “Given that the protective effect is less than in previous trials, patient selection and stroke risk prediction are crucial to optimal resource utilization in this high-risk population.”
Chang RW, Pimentel N, Tucker LY, et al. A comparative effectiveness study of carotid intervention for long-term stroke prevention in patients with severe asymptomatic stenosis from a large integrated health system. J Vasc Surg. Published online July 3, 2023. doi:10.1016/j.jvs.2023.06.024, et al.