Left ventricular dysfunction after mitral valve repair--the fallacy of "normal" preoperative myocardial function

A proportion of patients experience a decrease in left ventricular (LV) ejection fraction (EF) after mitral valve repair; however, predictors and long-term consequences remain unclear.

A study of 1705 patients with severe, degenerative mitral valve regurgitation and normal preoperative EF (>60%) undergoing mitral valve repair from 1993 to 2012 was performed. Multivariate logistic regression and Cox proportional hazards models were used to determine the predictors of early postoperative LV dysfunction (EF < 50%) and long-term survival, respectively.

Postoperative outcomes were comparable between patients; however, those with an EF of <50% (n = 314, 18.4%) had significantly greater enlargement in systolic dimension (left ventricular end-systolic diameter, -0.6 vs 4.3 mm; P < .001) and decrease in right ventricular systolic pressure (-2.7 vs -7.8 mm Hg; P < .001) immediately after repair. On longitudinal follow-up, early LV impairment persisted, with EF recovering to preoperative levels (>60%) in only one third of patients with postrepair EF <50% versus two thirds of those with an EF of ≥ 50% (P < .001). The overall survival at 5, 10, and 15 years of follow-up was 95%, 85%, and 70.8%, respectively. Although early postoperative EF < 50% was not a significant determinant of late survival, when adjusting for older age (hazard ratio [HR], 1.09), hypertension (HR, 1.38), New York Heart Association class III or IV (HR, 1.71), and preoperative atrial fibrillation (HR, 2.33), postoperative EF < 40% conferred a 70% increase in the hazard of late death (HR, 1.74; 95% confidence interval, 1.03-2.92; P = .037). A preoperative right ventricular systolic pressure >49 mm Hg and left ventricular end-systolic diameter >36 mm were independently associated with a 4.4- and 6.5-fold increased risk of developing a postoperative EF < 40% (P < .001, for both).

De novo postoperative LV dysfunction is not uncommon in patients with "normal" preoperative EF undergoing mitral valve repair. LV dysfunction can persist, impairing recovery of LV size, function, and survival. The consideration of mitral repair before the onset of excessive LV dilation or pulmonary hypertension, even in those with preserved EF, seems warranted.