Effects of mild ischemic mitral regurgitation on ventricular remodeling and its contribution to congestive heart failure.

Background: Although the prognostic impact of a moderate degree of ischemic mitral regurgitation (IMR) is well known, there are no data regarding the potential role of a mild degree of IMR. The aim of this study was to evaluate the impact of a mild degree (effective regurgitant orifice area < 20 mm(2)) of IMR on left ventricular (LV) remodeling and heart failure (HF).

Methods: A retrospective study was conducted in 35 patients with mild IMR that were propensity matched with 35 patients without IMR (controls). The population was evaluated between 3 and 6 months after first myocardial infarction and at 6 and 12 months, measuring LV volumes, ejection fraction, and the degree of mitral regurgitation. HF events requiring hospitalization were recorded.

Results: The two groups were similar at baseline. During follow-up, patients with IMR showed significant increases in LV end-diastolic and end-systolic volumes and no change in ejection fractions, whereas controls did not show significant changes in volumes but did show increases in ejection fractions. Patients with IMR showed significantly higher end-systolic volumes at 6 months (P = .003) and 12 months (P = .007) and significantly higher end-diastolic volumes at 6 months (P = .048) and 12 months (P = .03) and lower ejection fractions at 6 months (P = .0001) and 12 months (P = .002) compared with controls. Patients with IMR experienced a significantly higher incidence of HF than controls (62% vs 23%, P = .001). At 6 months, in six patients mitral regurgitation degree changed from mild to moderate, and in one patient from mild to severe. Interestingly, 71.5% of patients who experienced increases in mitral regurgitation degree had no coronary revascularization (P = .04).

Conclusions: Mild IMR affects the LV remodeling process, increases its degree over time, and determines a higher rate of HF.