Clinical Implications of Early Mitral Regurgitation in Patients With Reperfused Acute Myocardial Infarction

Abstract 

Background

The mechanisms by which mitral regurgitation (MR) may lead to an adverse prognosis after reperfused acute myocardial infarction (AMI) have not been fully investigated. We hypothesized that in the early phase of ST-elevation AMI, MR may lead to progressive left ventricular (LV) remodeling and subsequent heart failure.

Methods and Results

A series of 184 patients with AMI successfully treated with primary angioplasty underwent serial two-dimensional echocardiography at admission, at 1 and 6 months, and at 6-month angiography. The mean follow-up was 18 ± 7 months. On the basis of color Doppler, MR was graded from 0 (none) to 4 (severe). Patients were divided into group 1 (n = 146) with an MR grade of ≤ 1 and group 2 (n = 38) with an MR grade of ≥ 2. The regurgitant volume and effective regurgitant orifice area of MR were significantly higher in group 2 than in group 1 (36.7 ± 12.9 mL/beat vs 4.67 ± 3.2 mL/beat, P < .0001; 22.5 ± 7.6 mm² vs 5.8 ± 5.7 mm², P < .0001, respectively). LV end-diastolic volume progressively increased in group 2 and was significantly higher than in group 1 at 6 months (113.8 ± 31.8 mL vs 96.9 ± 34.1 mL, P = .0002), with a higher prevalence of LV remodeling (66% vs 22%, P < .0001). At 2 years, the incidence of heart failure was higher in group 2 than in group 1 (39% vs 12%, P < .0002). A significant correlation was found between effective regurgitant orifice area of MR and baseline to 6-month change of LV end-diastolic volume (P = .001). By stepwise multivariate regression analysis effective regurgitant orifice area of early MR was an independent predictor of LV remodeling (P = .001) and late heart failure (hazard ratio: 1.069, 95% confidence interval 1.033–1.106, P < .0001, Cox analysis).

Conclusion

In reperfused AMI, early high-degree MR is an important predictor of both LV dilation and subsequent heart failure.

Key Words: Angioplasty, heart failure, mitral regurgitation, myocardial infarction, remodeling