Although mitral regurgitation (MR) has been associated with an increased risk of death and heart failure after myocardial infarction (MI), the relationship between post-MI MR and left ventricular (LV) remodeling has not been entirely clarified. In addition, the optimal timing for assessing MR after MI remains unknown.

Post-MI MR was assessed by Doppler echocardiography at hospital discharge (baseline) and after 3 months in 261 patients with an inaugural anterior MI. We studied LV remodeling during a 1-year period and clinical follow-up after 3 years, according to MR severity at baseline and at 3 months.

Left ventricular remodeling was demonstrated as an increase in LV end-diastolic volume from 56 ± 15 mL/m² at baseline to 63 ± 19 mL/m² at 1 year (P < .0001). MR severity at baseline was not significantly associated with LV remodeling. By contrast, MR severity at 3 months was a strong indicator of LV remodeling. There was a graded increase in the proportion of patients with a >20% increase in LV end-diastolic volume between baseline and 1 year according to MR severity at 3 months (no MR: 21%, mild MR: 32%, moderate/severe MR: 60%) (P = .008).

Both MR at baseline and at 3 months were associated with death or rehospitalization for heart failure by univariate analysis (P = .014 and P < .0001, respectively). By multivariable analysis, MR at baseline was not an independent predictor of adverse outcome (P = .66). By contrast, MR at 3 months was independently associated with adverse outcome with a hazard ratio of 2.23 (1.02-4.91 [P = .04]).

After an inaugural anterior MI, MR is associated with LV remodeling and adverse clinical outcome. For prognostic purpose, the optimal timing for assessing MR is the chronic post-MI stage rather than the early post-MI period.