Abstract 12800: Increased Carotid Intima-Media Thickness and Presence of Carotid Plaque are Associated With Increased Stroke Incidence in Atrial Fibrillation: The Atherosclerosis Risk in Communities (ARIC) Study

Purpose: Increased carotid intima-media thickness (cIMT) and presence of carotid plaque are risk factors for incident ischemic stroke in the general population. We sought to determine whether these carotid indices are independently associated with incident ischemic stroke and improve risk prediction of stroke over and above the CHA 2 DS 2 -VASc variables in participants with incident atrial fibrillation (AF) in the ARIC study. Methods: We included participants who developed AF within 5 years after carotid evaluation (1987-98), not on warfarin, and without prior stroke at the time of AF diagnosis. Incident AF was ascertained from study ECGs and hospitalization discharge codes, and ischemic stroke was physician-adjudicated from medical chart review through the end of 2011. We used multivariable Cox models to assess association between carotid indices and ischemic stroke. We determined improvement in model discrimination by calculating the C statistic, net reclassification improvement (NRI) and relative integrated discrimination improvement (IDI) for 10-year risk prediction. Results: During a mean follow-up of 8.5 years, there were 724 incident AF cases (mean age 63, 40% female, 16% black), of whom 81 (11%) subsequently developed stroke. Increased cIMT and presence of carotid plaque were independently associated with increased risk of stroke in AF (Table). The addition of cIMT + plaque marginally improved discrimination of a model based on the CHA 2 DS 2 -VASc variables: C statistic (95% CI) improved from 0.685 (0.623-0.747) to 0.698 (0.638-0.759). The NRI and IDI for cIMT + plaque were statistically significant: 0.131 (0.01-0.226) and 0.101 (0.002-0.226), respectively (both p Conclusion: Increased cIMT and presence of carotid plaque are associated with increased risk of stroke in AF and modestly improve risk prediction of stroke. Further research is needed to evaluate whether carotid indices should be considered in current risk scores for stroke in AF.