Left Atrial Appendage Dimensions Predict the Risk of Stroke/TIA in Patients With Atrial Fibrillation

Abstract

Risk of Stroke/TIA in Patients With Atrial Fibrillation. Most strokes in patients with atrial fibrillation (AF) arise from thrombus formation in left atrial appendage (LAA). Our aim was to identify LAA features associated with a higher stroke risk in patients with AF using magnetic resonance imaging and angiography (MRI/MRA). The study included 144 patients with nonvalvular AF who were not receiving warfarin and who underwent MRI/MRA prior to catheter ablation for AF. LAA volume, LAA depth, short and long axes of LAA neck, and numbers of lobes were measured. Of the 144 patients, 18 had a prior stroke or transient ischemic attack (TIA) (13 and 5, respectively). Compared with patients who had no history of stroke/TIA, these patients were older, had higher prevalence of hypertension and hyperlipidemia and had higher LAA volume (22.9 ± 9.6 cm(3) vs. 14.5 ± 7.1 cm(3) , P < 0.001). Their LAA depth (3.76 ± 0.9 cm vs. 3.21 ± 0.8 cm, P = 0.006) and the long and short axes of the LAA neck (3.12 ± 0.7 cm vs. 2.08 ± 0.7 cm, P < 0.001; 2.06 ± 0.5 cm vs. 1.37 ± 0.4 cm, P < 0.001, respectively) were larger. Using stepwise logistic regression model, the only statistically significant multivariable predictors of events were age (OR = 1.21 per year, 95% CI 1.06-1.38, P = 0.004), aspirin use (OR = 0.039, 95% CI 0.005-0.28, P = 0.001), and LAA neck dimensions (short axis × long axis) (OR = 3.59 per cm(2) , 95% CI 1.93-6.69, P < 0.001). LAA dimensions predict strokes/TIAs in patients with AF. LAA assessment by MRI/MRA can potentially be used as an adjunctive tool for risk stratification for embolic events in AF patients.