Myocardial Performance Index Combining Systolic and Diastolic Myocardial Performance in Doxorubicin-Treated Patients and Its Correlation to Conventional Echo/Doppler Indices

Abstract

This study was designed to evaluate the utility of myocardial performance index (MPI) in anthracycline cardiotoxicity. The MPI measures the ratio of total time spent in isovolumic activity (isovolumetric contraction time and isovolumetric relaxation time) to the ejection time, thus giving a global index combining systolic and diastolic myocardial performance. In this study, MPI was measured in 35 doxorubicin-treated children (aged 108.5 ± 55.31 months, 23 males and 12 females) in sinus rhythm and 32 age-matched controls, and it was compared with conventional Doppler echocardiographic parameters. The isovolumetric contraction time was prolonged (38.37 ± 24.43 vs 26.37 ± 15.53, p <0.02) and ejection time was shortened (231.91 ± 28.87 VS 256.21 ± 19.55, P <0.001) in doxorubicin-treated patients compared to that in normal children. The isovolumetric relaxation time did not show significant difference between patients and control group (60.11 ± 10.92 vs 61.06 ± 12.12, P > 0.05). MPI was significantly increased in doxorubicin-treated patients compared with that in control groups (0.42 ± 0.07 vs 0.34 ± 0.06, p <0.001), and significant correlation was observed between MPI and fractional shortening, ejection fraction, and left ventricular end diastolic and end systolic diameters (respectively, R = -0.508, P <0.002; R = -0.532, P <0.001; R = 0.467 P <0.005; R=0.606, P <0.001). Also, a weak correlation was found between MPI and duration of the disease and patient ages (R = 0.393, P <0.02; R = 0.379; P <0.02). However, there was no correlation between MPI and cumulative doxorubicin dose (R = 0.311, P > 0.05) and diastolic Doppler parameters in doxorubicin-treated patients. We think that MPI may be a useful parameter in monitoring left ventricular dysfunction in anthracyline-treated patients.