Left atrial blood stasis by 4D flow MRI correlates with stroke risk estimation by CHA2DS2-VASc score

Background Stroke is the most serious complication of atrial fibrillation (AF). Of the estimated 600,000 ischemic strokes that occur each year in the United States, 15-20 percent are thought to be secondary to AF. Blood stasis is a key factor responsible for thrombus formation in the left atrium (LA). Studies utilizing transesophageal echocardiography have shown that peak left atrial appendage flow velocity < 0.2 m/s is an independent risk factor for stroke in AF. 4D Flow MRI may improve prediction of stroke risk in AF patients by examining 3D flow patterns across the entire LA volume over multiple phases spanning the cardiac cycle. We hypothesized that LA stasis measured by 4D flow MRI correlates with stroke risk estimated by the CHA2DS2-VASc clinical risk score in patients with AF.