Effect of mitral valve replacement on left ventricular function in subjects with severe rheumatic mitral regurgitation.

Abstract

Background. The outcome in patients with severe mitral regurgitation (MR) and impaired ejection fraction (EF) is poorly described in the developing world where rheumatic heart disease is endemic. Objective. This study describes the effects of mitral valve replacement (MVR) on left ventricular (LV) function in patients with rheumatic MR. Methods. This is a retrospective analysis of all subjects with severe rheumatic MR undergoing MVR over a 9 year period (2005-2013). Clinical and echocardiographic parameters were recorded pre-operatively, at 2 weeks, 6 weeks to 3 months and 6 months to 2 years following MVR. Results. Of 132 patients included in the study, 66% (n=87) were NYHA class III-IV, 38% (n=50) presented with clinical features of heart failure and 14% (n=19) had atrial fibrillation prior to MVR. The echocardiogram showed increased end systolic diameter (ESD, 39.9±7.2mm), left atrial size (LA, 61.2±12.6mm), and pulmonary artery systolic pressures (PASP, 59.5mmHg, IQR 45-80mmHg). Pre-operatively, 28% (n=37) of subjects had impaired LV function (EF <60%). At 6 months to 2 years following MVR (n=93), 1% of subjects were NYHA III-IV, 1% were in heart failure, and 7.6% had atrial fibrillation. Paired analysis of 83 patients with complete datasets revealed that the EF was >55% in 87% (n=72) pre-operatively, the number of patients with EF >55% dropped to 20% (n=17) at 2 weeks postoperatively (p<0.001, 95% CI 0.02-0.09) and thereafter an EF > 55% was recorded in 60% (n=53) at the 6 months to 2 year follow up (p<0.001, 95% CI 0.1-0.5). After feeding all clinical and echocardiographic variables into a predictive model only the ESD emerged as a significant predictor of postoperative LV dysfunction (EF< 50%) both on uni- and multivariate analysis. Conclusion. Most subjects with severe rheumatic MR who were subjected to surgery had advanced disease with heart failure, indicating that preoperatively, impairment of LV function was a frequent finding. The preoperative ESD was the only predictor of postoperative LV dysfunction. This study calls for careful clinical assessment with regular imaging and early referral for surgery in subjects with severe MR according to established guidelines in order to ensure preservation of ventricular function.