Identification of Markers Associated With Development of Stroke in "Clinically Low-Risk" Atrial Fibrillation Patients.

Background-Stroke and thromboembolic events may still occur in "clinically low-risk" atrial fibrillation (AF) patients as categorized by CHA(2)DS(2)-VASc score. Our aim was to assess the proportion of "clinically low-risk" patients using a nongender CHA(2)DS(2)-VASc (ie, CHA(2)DS(2)-VA) score of 0 to 1 among patients who experienced AF-associated stroke and to identify markers associated with stroke in "clinically low-risk" patients. Methods and Results-We retrospectively recruited nonvalvular AF patients who experienced embolic stroke between 2013 and 2016 from 9 institutes in Korea. AF patients with CHA(2)DS(2)-VA score of 0 to 1 at the time of stroke were analyzed and compared with "clinically low-risk" AF patients without stroke. A total of 3033 subjects with AF-associated stroke were recruited. Of these, 583 patients (19.2%) had CHA(2)DS(2)-VA score of 0 to 1. On multivariate analysis, age (>= 60 years), N-terminal pro B-type natriuretic peptide (>= 300 pg/mL), creatinine clearance (<50 mL/min), and left atrial dimension (>= 45 mm) were independently associated with stroke. With the combined application of these 4 factors (collectively, ABCD score) to the "clinically low-risk" patients, the c-index was 0.858 (95% CI 0.838-0.877; P<0.001). Conclusions-The present study suggests a new insight into how additional use of markers can further refine stroke risk differentiation among AF patients initially classified as "clinically low-risk."