Mortality and morbidity after mitral valve repair: the importance of left ventricular dysfunction

A retrospective study of 219 consecutive patients who underwent mitral valve repair for mitral regurgitation or mixed mitral valve disease with at least moderate regurgitation was undertaken. The etiology was degenerative in 151 (68.9%) patients, endocarditis in 24 (10.9%), rheumatic in 22 (10.0%), ischemic in 13 (5.9%), congenital in five (2.3%) and cardiomyopathy in two (0.9%). The average age was 64.8 +/- 10.9 years, the average follow up 30.2 +/- 24.1 months. Pre-operatively, 74% were in NYHA functional class III or IV. Left ventricular function was assessed by angiography and echocardiography, and moderate or severe impairment (ejection fraction < or = 40%) was assumed to represent significant left ventricular dysfunction. There were six (2.7%) hospital deaths, four of which were due to left ventricular dysfunction. The seven-year mortality and seven-year combined mortality and morbidity were 14.4% and 37.1% respectively for complications related to left ventricular dysfunction, and 2.5% and 24.2% respectively for unrelated complications. Subgroup analysis showed that five-year mortality and five-year combined mortality and morbidity due to left ventricular dysfunction were significantly worse in patients who had pre-operative left ventricular dysfunction than those who did not: 28.5% vs. 6.1% (p < 0.001) and 52.4% vs. 17.8% (p < 0.001). There was nevertheless a significant incidence of postoperative left ventricular dysfunction in patients with satisfactory preoperative left ventricular function. In this group, five-year mortality and five-year combined mortality and morbidity due to left ventricular dysfunction were higher in patients who were in NYHA class III or IV preoperatively than in those who were not: 11.2% vs. 0% (NS) and 25.9% vs. 0% (p < 0.01) respectively, particularly if they also had early (3-10 days) post-operative left ventricular dysfunction: 20.4% (p < 0.001) and 41.7% (p < 0.001) respectively. Despite preservation of the mitral apparatus, left ventricular dysfunction remains a major cause of mortality and morbidity following mitral valve repair for mitral regurgitation.