Ischemic mitral regurgitation (MR) is a known complication of ST-segment elevation myocardial infarction (STEMI) with important prognostic implications. We evaluated changes over time in ischemic MR after STEMI and the prevalence and predictors of significant (grade ≥2) MR at 12 months. Furthermore, the prognostic additional value of significant MR at 12-month follow-up over acute MR was assessed.

STEMI patients (n = 1,599; 77% male; 60 ± 12 years) treated with primary percutaneous coronary intervention underwent echocardiography <48 hours of admission (baseline) and at 12 months. Mortality data were collected during long-term follow-up.

At baseline, significant MR was present in 103 (6%) patients. After 12 months, MR worsened ≥1 grade in 321 (20%) patients, remained stable in 963 (60%), and improved ≥1 grade in 315 (20%). Significant MR was present in 135 patients at 12 months (8%, P = .01 vs baseline). Age, left ventricular end-systolic volume, and significant MR at baseline were independently associated with significant MR at follow-up. During follow-up (median, 50 months), 121 (8%) patients died (40% of cardiovascular cause). Significant MR at follow-up was independently associated with all-cause (hazard ratio, 1.65, 95% CI, 1.02-2.99) and cardiovascular mortality (hazard ratio, 2.47; 95% CI, 1.24-4.92), also after adjusting for significant MR at baseline.

The prevalence of significant MR after STEMI increases over time. Age, baseline left ventricular end-systolic volume, and baseline significant MR are independently associated with significant MR at follow-up. Significant MR at 12 months is associated with subsequent all-cause and cardiovascular mortality and shows additional prognostic value over acute MR.