Atrial fibrillation and stroke: importance of left atrium as assessed by echocardiography

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, which has been increasing dramatically. AF has unfavorable consequences, such as stroke, heart failure, and cardiovascular death. Of these, stroke has been considered to be the serious complication. Recently, direct oral anticoagulation or new technologies, such as the WATCHMAN left atrium (LA) appendage closure device, have emerged to prevent stroke. Therefore, the accurate estimation of thromboembolic risk and appropriate prevention are essential for high-risk patients with AF. Although CHADS₂ and CHA₂DS₂-VASc scores has been widely used to predict the risk of stroke in patients with AF, some researchers showed that there was no relationship between CHADS₂ and CHA₂DS₂-VASc scores and LA appendage thrombus formation. Recent studies have reported that combination of echocardiographic parameters to CHADS₂ or CHA₂DS₂-VASc scores can stratify high risk groups for LA appendage thrombus formation and onset of stroke. In this review, we focus on the epidemiological, pathophysiological, and prognostic associations between AF and stroke, and review the clinical and echocardiographic predictors for stroke in patients with AF.