Coronary artery calcium and carotid artery intima-media thickness for the prediction of stroke and benefit from statins

Background: Current guidelines suggest treatment for many individuals who may never develop a stroke. We hypothesized that a combination of coronary artery calcification (CAC) and carotid artery intima-media thickness (CIMT) data could better individualize risk assessment for ischemic stroke and transient ischemic attack events. Methods: A total of 4720 individuals from the Multi-Ethnic Study of Atherosclerosis were evaluated for ischemic stroke and transient ischemic attack. Cox proportional hazards models for time to incident ischemic stroke/transient ischemic attack were used to examine CAC and CIMT as ischemic stroke/transient ischemic attack predictors in addition to traditional risk factors. We calculated the 10-year number needed to treat by applying the benefit observed in ASCOT-LLA to the observed event rates within CAC and CIMT strata. Results: Median follow-up was 13.1 years. Compared with individuals with no CAC and with CIMT ≤ 75th percentile, stroke/transient ischemic attack risk increased progressively with each CAC category (0, 1–100, >100) among individuals with CIMT > 75th percentile. Among participants eligible for statin therapy based on the 2013 atherosclerotic cardiovascular disease (ASCVD) guidelines (ASCVD risk of >5%), 739/2906 (25%) had no CAC and CIMT ≤ 75th percentile and an observed ischemic stroke/transient ischemic attack rate of 2.49 per 1000 person-years. The predicted 10-year number needed to treat was 292 for no CAC and CIMT ≤ 75th percentile and 57 for CAC > 100 and CIMT > 75th percentile. Conclusion: The combination of CIMT and CAC could serve to further refine risk calculation for ischemic stroke/transient ischemic attack prevention and may prioritize those in most need of statin therapy to reduce ischemic stroke/transient ischemic attack risk.