Abstract 3332: Left Atrial Size Predicts Outcome in Asymptomatic Severe Mitral Regurgitation
Background: Left atrial (LA) size is affected by left ventricular (LV) diastolic pressure, ventricular remodeling, atrial fibrillation and mitral regurgitation (MR) itself. LA size has been proposed to be a predictor of outcome after mitral valve replacement with preserved LV function. However, the predictive value of LA size for development of symptoms or LV dysfunction among pts with severe MR has not been studied.
Methods: 132 consecutive asymptomatic pts (age 55±15 yrs, 49 female) with severe degenerative MR and normal LV function were prospectively followed for a median of 69 months. Pts underwent serial clinical and echocardiographic exams. The following potential predictors of outcome were studied: LA size, LV diameter, pulmonary artery pressure and clinical risk factors.
Results: Kaplan-Meier event-free survival for the entire pt. group, with endpoints defined as development of symptoms or LV dysfunction (n=38) and death related to MR (n=0) was 92±2% at 2 yrs, 78±4% at 4yrs, 65±5 at 6 yrs and 55±6% at 8 yrs. LA size was the strongest independent predictor of outcome: No events were observed in the group with a LA < 50 mm. Event-free survival for patients with LA 50 to 69 mm was 94±3% at 2 yrs, 82±5% at 4 and 51±8% at 8 yrs versus 85±8% at 2 yrs, 47±12% at 4yrs and 40±12% at 8 yrs for patients with a LA ≥ 70 mm (p=0.0001). None of the other studied parameters reached significance as predictors of outcome in multivariate analysis.
Conclusion: LA size is a strong and independent predictor of outcome in patients with asymptomatic severe MR. Patients can be stratified by LA size into groups at low, intermediate and high risk for subsequent symptom or LV dysfunction development, requiring surgery.