Abstract 11553: The CHA2DS2-VASc Score and the Risk of Ischemic Stroke by Atrial Fibrillation Status: The Atherosclerosis Risk in Communities (ARIC) Study

Abstract

Background: CHA2DS2-VASc score has been shown to be predictive of risk of ischemic stroke (IS) in persons without atrial fibrillation (AF). These observations raise the question whether it is AF per se or the associated vascular risk factors that elevate the risk of IS. Hypothesis: AF elevates the risk of IS over and above vascular risk factors in the CHA2DS2-VASc score and as the CHA2DS2-VASc score increases, AF plays a more important role in determining the risk of stroke. Methods: Using the ARIC study_a biracial, community-based prospective cohort study we compared (a) the model discrimination of the CHA2DS2-VASc score for IS in participants with vs. without AF, and (b) the risk of IS by CHA2DS2-VASc score among participants with vs. without AF. We included 1395 participants with AF who were matched to 4060 participants without AF based on age, race, and CHA2DS2-VASc score (mean age, 62 years; 57% women; 22% blacks). Participants with prevalent IS or anticoagulant use at baseline were excluded. AF was ascertained from hospitalization discharge codes and study ECGs. IS was physician-adjudicated. Results: Median follow-up was 14.7 years and 288 (5.3%) participants developed IS. The C-statistic of the CHA2DS2-VASc score for IS was not significantly different in participants with vs. without AF (Table). The incidence rate difference of IS increases with increasing CHA2DS2-VASc score in participants with vs. without AF (Table, p for interaction between AF and CHA2DS2-VASc score <0.0001). Conclusion: Model discrimination of the CHA2DS2-VASc score for IS in individuals with AF is comparable to those without AF. However, with increasing score, the incidence rate of IS in individuals with AF increases to a greater extent than in those without AF. These findings suggest that as the CHA2DS2-VASc score increases, the disorganized rhythm of AF or other AF-related factor (e.g., left atrial dysfunction or enlargement) plays an even greater role to elevate the risk of IS.