LAUSR

Abstract Funding Acknowledgements Type of funding sources: None. Background/Introduction Anticoagulant therapy has been important for stroke prevention in patients with atrial fibrillation (AF). However, it was not recommended due to its relatively higher risk of bleeding than its lower risk of stroke in patients with a CHA2DS2-VASc score of 0. Purpose This study aimed to evaluate the predictors of stroke in AF patients with very low risk of stroke. Methods Between 1990 and 2020, 542 patients with non-valvular AF (NVAF) with a CHA2DS2-VASc score of 0 followed up for at least 6 months were enrolled. Patients whose only risk factor was female were included as a CHA2DS2-VASc score of 0 in this study. The primary outcome was stroke or systemic embolism. Results The mean age at AF diagnosis was 49.9 years, and 398 (73.4%) were men. During the mean follow-up of 4.7 years, the primary outcome rate was 0.78%/year (stroke, 0.70%/year; systemic embolism, 0.08%/year), and major bleeding and all-cause death occurred in 0.31%/year and 1.02%/year, respectively. The proportions of age ≥50 years at diagnosis, left ventricular end-diastolic dimension (LVEDD) of ≥46 mm, and non-paroxysmal AF in patients with stroke or systemic embolism were significantly higher than in those without. Cox proportional hazard model, age of ≥50 years at diagnosis (hazard ratio [HR] 6.710, 95% confidence interval [CI] 1.811–24.860, P-value=0.004), LVEDD of ≥46 mm (HR 4.513, 95% CI 1.038–19.626, P-value=0.045), and non-paroxysmal AF (HR 5.575, 95% CI 1.621–19.175, P-value=0.006) were identified as independent predictors of stroke or systemic embolism. Patients with all three independent predictors had a higher risk of stroke or systemic embolism (4.21%/year), whereas those without did not have stroke or systemic embolism. Conclusion The annual stroke or systemic embolism rate in NVAF patients with CHA2DS2-VASc score of 0 was 0.78%/year. Age at AF diagnosis, LVEDD, and non-paroxysmal AF were independent predictors of stroke or systemic embolism in patients considered to be at very low risk of stroke. Risk of stroke/systemic embolism Annual rates of stroke/systemic embolism