Effect of Pulmonary Vascular Pressures on Long-Term Outcome in Patients With Primary Mitral Regurgitation

Background Primary mitral regurgitation (MR) is a growing health problem due to the aging population. Objectives The purpose of this study was to assess the impact of baseline pulmonary hypertension on long-term outcomes in patients with significant primary MR and preserved left ventricular ejection fraction (LVEF). Methods We studied 1,318 patients with ≥3+ primary MR and LVEF ≥60% using echocardiography at rest; they were evaluated at our center from 2005 to 2008. Baseline clinical and echocardiography data were recorded, and the Society of Thoracic Surgeons (STS) score was calculated. The primary outcome was death. Results Mean STS score was 3.98 ± 1%; 54% of patients were in New York Heart Association (NYHA) functional class I and 31% were in NYHA functional class II; and 18% had atrial fibrillation (AF). Mean LVEF, mitral effective regurgitant orifice, indexed LV end-systolic diameter (LVESD), and right ventricular systolic pressure (RVSP) were 62 ± 2%, 0.56 ± 0.30 cm², 1.6 ± 0.3 cm/m², and 37 ± 14 mm Hg, respectively. At 7.1 ± 2.0 years, 86% had mitral valve (MV) surgery. Death occurred in 130 (10%) patients. On Cox multivariable analysis, baseline RVSP, together with age, baseline NYHA functional class, pre-operative AF, coronary artery disease, and indexed LVESD were associated with a higher rate of longer term mortality (all p < 0.01), whereas MV surgery (as a time-dependent covariate) was associated with improved survival (p < 0.001). Addition of RVSP to the STS score significantly reclassified the risk for longer term mortality (integrated discrimination index: 0.07; p < 0.001); 77% patients who died had RVSP ≥35 mm Hg. Conclusions In patients with significant primary MR and preserved LVEF, baseline RVSP is independently associated with long-term survival. Impact of RVSP is progressive and not confined to those with the highest baseline values.