Value of the New Doppler – Derived Myocardial Performance Index in Predicting Subclinical Cardio- toxicity in Children Treated with Anthracyclines

BackgroundThere are many limitations to the use of conventional echocardiography indices for the estimation of systolic and diastolic left ventricular (LV) function. Anthracycline chemotherapy causes myocardial damage, leading to acute or chronic congestive heart failure during or soon after treatment in a significant percentage of patients treated, depending on the total cumulative dose used. The aim of this study was to determine the usefulness of myocardial performance index (MPI) in evaluation of subclinical cardiotoxicity in patients undergoing chemotherapy with anthracyclines. MethodsSeventy-five patients (41 male, 34 female, mean age 9±3 years) with malignant solid tumors and hematologic malignancy were randomly selected and evaluated before, during and after therapy by 2-D, M-Mode and Doppler echocardiography; and the data were compared with 48 ageand sex-matched normal controls prospectively. ResultsTwenty-three patients were taking high doses of anthracyclines (>200mg/m), whereas 52 patients were taking low doses of anthracyclines (<200mg/m). Mean dose of anthracyclines in all the patients was 140±60mg/m. IVCT was prolonged (42±11msec vs. 28±8msec, P-value=0.018) compared with normal control subjects. ET was shortened (220±24msec vs. 234±14msec, Pvalue=0.025), and MPI was increased in the anthracycline-treated patients compared with normal control subjects (0.44±0.06 vs. 0.34±0.04, P-value =0.015). Also, we found no correlation between MPI and cumulative dose of anthracyclines in 52 patients taking lower doses (<200mg/m) compared with 23 patients taking higher doses (>200mg/m); MPI was 0.42±0.04 vs. 0.44±0.08, with P-value =0.062 between the two groups. No significant difference was found in LVEF (0.58 ± 0.12 vs. 0.64±0.06, P-value=0.056) and LVFS (0.32±0.08 vs. 0.36±0.04, Pvalue=0.068) between the patients and normal controls. ConclusionThe findings of this study suggest that anthracycline cardiotoxicity is subtle and subclinical and systolic functions are preserved. MPI is helpful in the discrimination of early cardiac involvement from anthracycline chemotherapy, especially in asymptomatic young patients with normal limited systolic function. Moreover, MPI can enhance the accuracy of echocardiographic diagnosis in early ventricular dysfunction. Cumulative dose of anthracyclines is not a suitable parameter in the determination of the risk of the severity of anthracycline cardiotoxicity. Recent advantages in diagnostic tests have allowed diagnosis at early stages of disease before massive cell injury and irreversible changes occur (Iranian Heart Journal 2006; 7 (4): 43-48).