Outcomes of mitral valve reoperation and first-time surgery for mitral regurgitation: A nationwide study

BACKGROUND: While mitral reoperation has been assumed to carry higher surgical risk than first-time mitral surgery, outcomes of this procedure remain uncertain. AIMS: To examine characteristics and outcomes associated with mitral valve reoperation and first-time surgery for mitral regurgitation. METHODS: Patients undergoing surgery for mitral regurgitation were identified using Danish nationwide registries. The population was categorized into 1) patients undergoing first-time mitral surgery, 2) patients undergoing mitral reoperation. Mortality rates were examined during 180-day follow-up using Reverse Kaplan-Meier and Multivariable Cox-analysis. RESULTS: In total, 7734 patients underwent surgery for mitral regurgitation. Of these, 428 patients also underwent mitral reoperation. Compared to first-time surgery, reoperated patients were younger (median 64.9 and 66.7 years) and had more cardiovascular comorbidities including atrial fibrillation (61.6 % and 38.8 %) and heart failure (48.7 % and 29.9 %). Median time to reoperation was 2.3 years. Prosthetic replacement was performed in 34.0 % of first-time surgeries and 78.7 % of reoperations. Mortality was 7.1 % following first-time surgery and 10.1 % following reoperation. Following first-time surgery, factors associated with increased mortality rate was prior myocardial infarction (HR = 1.98, 95 %CI 1.62-2.41), heart failure (HR = 1.59, 95 %CI 1.33-1.90), concomitant aortic valve surgery (HR = 1.61-1.27, 95 % CI 1.27-2.02) and bypass grafting (HR = 1.58, 95 %CI 1.31-1.91). Following reoperation, heart failure was associated with increased mortality rate (HR = 2.23, 95 %CI 1.17-4.60). CONCLUSIONS: Patients undergoing mitral reoperation are young but have developed high burden of comorbidities at the time of reoperation. In spite of this, outcomes of mitral reoperation were acceptable, reflecting that this procedure can be performed safely in selected patients.