Usefulness of left atrial appendage volume as a predictor of embolic stroke in patients with atrial fibrillation.

Stroke prevention in atrial fibrillation (AF) is guided by clinical factors with inadequate predictive power. Most thrombi observed in AF are observed in the left atrial appendage (LAA). This study was designed to determine (1) the association between LAA and the incidence of AF-related stroke and (2) the power of LAA to predict stroke. Patients (n = 48) with a history of AF and stroke were compared with control subjects (n = 48) with a history of AF but no history of stroke. Magnetic resonance images from both case and control populations were manually segmented to determine LAA volume. Patients with a history of stroke had larger LAA mean volumes than control subjects (28.8 ± 13.5 cm(3) vs 21.7 ± 8.27 cm(3), p = 0.002). Stroke risk is highest in patients with a LAA volume >34 cm(3) (multivariable OR 7.11, p = 0.003). In conclusion, larger LAA volume is associated with stroke in the setting of AF, and this measure can potentially improve risk stratification for stroke risk management in AF patients.