Abstract 2291: Left Atrial Volume Is a Strong Predictor of Outcome in Patients with Organic Mitral Regurgitation
Background: In patients with organic mitral regurgitation (MR) left atrial (LA) enlargement is considered a physiologic response to volume overload but its impact on clinical outcome is poorly defined. Whether LA enlargement predicts mortality or cardiac events after diagnosis remains uncertain.
Methods: 492 patients (63±15 years, 60% males) in sinus rhythm with organic MR of at least mild degree were prospectively enrolled. MR was quantified according to current recommendations. LA volume was quantified by the apical biplane area-length method and indexed to body surface area (LA-index). The end-points were overall mortality, and cardiac death/heart failure/AF (cardiac event) under medical management.
Results: Etiology was mitral valve prolapse in 398 patients (81%). Mean MR volume was 68±42 ml, effective regurgitant orifice 42±29 mm2. Left ventricular (LV) end-diastolic (ED) diameter averaged 56±8 mm, LVED volume 205±61 ml, and LVEF 69±8%. LAVol was 103±49 ml, LA-index 55±26 ml/m2 and LA-index was ≥ 60 ml/m2 in 174 patients (35%). At 5-year mortality was 19.7% and cardiac event was 31.7% under medical treatment. In patients with (vs. without) LA-index ≥ 60 ml/m2, 5-year mortality (47.0 vs. 12.4%, p<0.0001) and cardiac events (69.3 vs. 10.8%, P<0.0001) were markedly increased. LA-index ≥ 60 ml/m2, univariately and adjusting for age, gender, symptoms, LVEF and regurgitant volume independently predicted mortality (HR 2.8[1.2– 6.5], P=0.016) or cardiac events (HR 3.5[1.8 – 6.7], P<0.0001).
Conclusion: In organic MR, LA-index at diagnosis is an important measure of volume overload and predicts long-term outcome under medical management, incrementally to other known predictors of outcome. LAVol measurement should be standard in patients with organic MR. As a novel marker of risk under medical management, LA-index should be used in considering surgical treatment of patients with organic MR.