Myocardial Performance Index and Atrial Ejection Force in Patients with Duchenne's Muscular Dystrophy

Abstract

Progressive movement limitation in patients with Duchenne's muscular dystrophy (DMD) may mask the onset of cardiac involvement. We aimed to determine whether myocardial performance index (MPI), either by conventional Doppler (CD) or tissue Doppler imaging (TDI), could detect subclinical myocardial dysfunction in DMD patients. Furthermore, we assessed the atrial ejection force (AEF) to evaluate possible existence of latent diastolic dysfunction. Twenty DMD patients without signs and symptoms of cardiac impairment and 20 age matched control group enrolled into the study. MPI for right ventricle and left ventricle (LV) was assessed with CD and TDI for comparison. No significant difference was detected in ejection fraction, fractional shortening, and AEF between two groups. CD derived MPI was higher for both ventricles in the patients (P < 0.0001). Moreover, the TDI derived MPI were significantly higher in the patients in mitral, tricuspid, and septal views (P < 0.0001). A significant decrease of mitral myocardial systolic wave velocity was detected in the patients, in favor of early involvement of the posterobasal LV myocardium. All acceleration and deceleration times' values for the late mitral inflow were higher whereas the rates were significantly lower in the patients. There was no significant difference between AEF of both groups. MPI might be a useful parameter for early detection of occult cardiac dysfunction in DMD patients when other simple and standard echocardiographic parameters are within the normal limits. Lack of atrial contribution in LV filling due to atrial contractile dysfunction may play a role in DMD cardiac dysfunction.