P3755Left atrial enlargement as an independent risk factor for ischemic stroke in Japanese atrial fibrillation patients: pooled analysis of five major Japanese atrial fibrillation registries

Abstract Background Atrial fibrillation (AF) increases the risk of ischemic stroke. It remains unknown whether left atrial diameter determined by routine trans-thoracic echocardiography is a risk factor for ischemic stroke in non-valvular AF (NVAF) patients. Purpose The aim of this study is to investigate the impact of left atrial enlargement (LAE) on the incidence of ischemic stroke in a large-scale cohort of Japanese NVAF patients. Methods We combined the data of 5 major AF registries in Japan, J-RHYTHM Registry, Fushimi AF Registry, Shinken Database, Keio interhospital Cardiovascular Studies, and Hokuriku AF Registry. After excluding patients without echocardiographic data, 7,672 NVAF patients were analyzed in the present study (mean age, 69.3±12.3 years; mean CHADS2 score, 1.6±1.3). We compared clinical characteristics and the incidence of ischemic stroke between NVAF patients with LAE (left atrial diameter >45 mm; LAE group) and those without (non-LAE group). Results The mean left atrial diameter was 43.1±8.6 mm, and the LAE group accounted for 40.0% (n=3,066) of the entire cohort. Compared with non-LAE group (60.0%, n=4,606), the LAE group was older (LAE vs. non-LAE; 70.3±12.0 vs. 68.0±12.5, p<0.01), more often non-paroxysmal type (73.7% vs. 32.1%, p<0.01), had higher CHADS2 (1.86±1.34 vs. 1.46±1.29, p<0.01) and CHA2DS2-VASc (3.02±1.83 vs. 2.53±1.78, p<0.01) scores, and more frequently received oral anticoagulant (72.9% vs. 55.0%, p<0.01). During the median follow-up period of 774.5 days (interquartile range: 567–1466 days), ischemic stroke occurred in 241 patients (131 vs. 110 patients; 1.52 vs. 0.82 per 100 person-years). In Kaplan Meier analysis, LAE was associated with a higher incidence of ischemic stroke (unadjusted hazard ratio (HR): 1.83, 95% confidence interval (CI): 1.42–2.36; log rank p<0.01) (Figure). LAE was independently associated with increased risk of ischemic stroke (adjusted HR: 1.63, 95% CI: 1.25–2.11; p<0.01) after adjustment by the components of CHADS2 score and the use of oral anticoagulant, on multivariate Cox proportional hazard analysis. Conclusion In this large-scale cohort of Japanese patients with AF, LAE was an independent predictor of ischemic stroke, suggesting that this simple echocardiographic parameter could refine thromboembolic risk stratification of NVAF patients. Acknowledgement/Funding Japan Agency for Medical Research and Development, AMED