Temporal Trends and Determinants of Stroke Risk in Patients With Medically Treated Asymptomatic Carotid Stenosis.

BACKGROUND: Effectiveness of carotid procedures (surgery and stenting) in patients with asymptomatic carotid artery stenosis (ACAS) depends on the absolute risk reduction that patients might receive from these procedures. We aimed to quantify the risk of ipsilateral ischemic stroke and examined temporal trends and determinants of these risks in patients with ACAS treated conservatively. METHODS: We conducted a systematic review from inception to March 9, 2023, of peer-reviewed trials and cohort studies describing ipsilateral ischemic stroke risk in medically treated patients with ACAS of ≥50%. Risk of bias was assessed with an adapted version of the Quality in Prognosis Studies tool. We calculated the annual incidence rates of ipsilateral ischemic stroke. We explored temporal trends and associations of sex and degree of stenosis with ipsilateral ischemic stroke using Poisson metaregression analysis and incidence rate ratios, respectively. RESULTS: After screening 5915 reports, 73 studies describing ipsilateral ischemic stroke rates of 28 625 patients with midyear of recruitment ranging from 1976 to 2014 were included. The incidence of ipsilateral ischemic stroke was 0.98 (95% CI, 0.93-1.04) per 100 patient-years (median duration of follow-up, 3.3 years). The incidence decreased 24% with every 5 years more recent midyear of recruitment (rate ratio, 0.76 [95% CI, 0.73-0.78]). Incidence rates of ipsilateral ischemic stroke were lower in female patients (rate ratio, 0.74 [95% CI, 0.63-0.87]) and in patients with moderate versus severe stenosis when assessed in cohort studies, with incidence rate ratios of 0.41 ([95% CI, 0.35-0.49] cutoff, 70%) and 0.42 ([95% CI, 0.30-0.59] cutoff, 80%). CONCLUSIONS: Reported risks of ipsilateral ischemic stroke in patients with ACAS have declined 24% every 5 years from mid-1970s onward, further challenging the routine use of carotid procedures. Risks were lower in female patients and more than twice as high with severe compared with moderate ACAS. Inclusion of these findings in individualized risk assessment can help to determine the benefit of carotid procedures in selected individual patients with ACAS. REGISTRATION: URL: https://www.crd.york.ac.uk/PROSPERO/; Unique identifier: CRD42021222940.

External Validation of Risk Prediction Models to Improve Selection of Patients for Carotid Endarterectomy.

BACKGROUND AND PURPOSE: The net benefit of carotid endarterectomy (CEA) is determined partly by the risk of procedural stroke or death. Current guidelines recommend CEA if 30-day risks are <6% for symptomatic stenosis and <3% for asymptomatic stenosis. We aimed to identify prediction models for procedural stroke or death after CEA and to externally validate these models in a large registry of patients from the United States. METHODS: We conducted a systematic search in MEDLINE and EMBASE for prediction models of procedural outcomes after CEA. We validated these models with data from patients who underwent CEA in the American College of Surgeons National Surgical Quality Improvement Program (2011-2017). We assessed discrimination using C statistics and calibration graphically. We determined the number of patients with predicted risks that exceeded recommended thresholds of procedural risks to perform CEA. RESULTS: After screening 788 reports, 15 studies describing 17 prediction models were included. Nine were developed in populations including both asymptomatic and symptomatic patients, 2 in symptomatic and 5 in asymptomatic populations. In the external validation cohort of 26 293 patients who underwent CEA, 702 (2.7%) developed a stroke or died within 30-days. C statistics varied between 0.52 and 0.64 using all patients, between 0.51 and 0.59 using symptomatic patients, and between 0.49 to 0.58 using asymptomatic patients. The Ontario Carotid Endarterectomy Registry model that included symptomatic status, diabetes, heart failure, and contralateral occlusion as predictors, had C statistic of 0.64 and the best concordance between predicted and observed risks. This model identified 4.5% of symptomatic and 2.1% of asymptomatic patients with procedural risks that exceeded recommended thresholds. CONCLUSIONS: Of the 17 externally validated prediction models, the Ontario Carotid Endarterectomy Registry risk model had most reliable predictions of procedural stroke or death after CEA and can inform patients about procedural hazards and help focus CEA toward patients who would benefit most from it.