Correlation of the myocardial performance index with plasma B-type natriuretic peptide levels in patients with mitral regurgitation

Abstract

Objective: The Myocardial performance index (MPI) is an echocardiographic index of combined systolic and diastolic function, calculated as isovolumetric relaxation time plus isovolumetric contraction time divided by ejection time. The aim of this study was to define the correlation of the MPI with plasma B-type natriuretic peptide (BNP) levels and echocardiographic parameters in patients with chronic mitral regurgitation (MR).

Methods: About 33 patients with at least moderate MR of organic etiology were enrolled to the study. All patients undergone complete 2D and Doppler echocardiography. Plasma BNP levels were studied.

Results: BNP levels in NYHA classes I-III were 9.3 +/- 2.2 pg/ml, 61.3 +/- 12.2 pg/ml, and 199.6 +/- 55.2 pg/ml, respectively (I vs. II P < 0.001, I vs. III P < 0.001 and II vs. III P = 0.004). Myocardial performance index were 0.42 +/- 0.02, 0.49 +/- 0.02, and 0.52 +/- 0.03 in MR patients with NYHA I-III, respectively. MPI was significantly higher in patients with NYHA class III compared to NYHA I (P = 0.001) and NYHA II (P = 0.005). There were no correlations between MPI and left atrial diameter, MR jet area, MR index and systolic pulmonary artery pressure whereas left ventricle (LV) end-systolic volume (r = 0.38), LV end-diastolic volume (LVDV) (r = 0.40), LV ejection fraction (r = -0.59), NYHA class (r = 0.51) and plasma BNP levels (r = 0.67) were strongly correlated. Only independent variable affecting MPI was plasma BNP level (odds ratio [CI]: 2.18[0.002-0.098], P = 0.041).

Conclusions: MPI is a powerful index in assessing the severity of left ventricular function and symptom severity in patients with MR. Plasma BNP is an independent predictor of MPI where both parameters assess combined systolic and diastolic LV function, effectively.