Impact of functional mitral regurgitation on right ventricular function and outcome in patients with right ventricular infarction

Right ventricular (RV) infarction is associated with increased mortality. Functional mitral regurgitation (FMR) may complicate inferoposterior infarction with RV involvement leading to pulmonary hypertension and increased RV afterload, potentially exacerbating RV remodeling and dysfunction. We studied 179 patients with inferior wall left ventricular (LV) ST-elevation myocardial infarction and RV infarction. The presence and severity of FMR and RV function were assessed by echocardiography. FMR was diagnosed based on echocardiographic criteria and when the severity of regurgitation was ≥moderate. Eighteen patients (10.0%) had ≥moderate FMR. Estimated pulmonary artery systolic pressure was higher in patients with FMR than in patients without FMR (43 ± 10 vs 34 ± 10 mmHg, respectively, p = 0.002). RV systolic dysfunction was present in 76 patients (42.5%). FMR was a strong predictor of RV dysfunction (odds ratio 5.35, 95% confidence interval [CI] 1.65 to 17.48, p = 0.005) independent of reperfusion therapy. During a median follow-up of 4.1 years, 20 (12.4%) and 10 (55.6%) deaths occurred in patients with and without FMR, respectively (p <0.001). In a multivariable Cox regression model, compared with patients without FMR and with normal RV function, the adjusted hazard ratio for mortality was 1.02 in patients without FMR and with RV dysfunction (95% CI 0.39 to 2.69, p = 0.97) and 3.62 in patients with FMR with RV dysfunction (95% CI 1.33 to 9.85, p = 0.01). In conclusion, in patients with RV infarction, the development of concomitant hemodynamically significant FMR is associated with RV dysfunction. The risk for mortality is increased predominantly in patients with both RV dysfunction and FMR.