QT Dispersion after Chemotherapy with Anthracyclines in Children

ABSTRACT

PURPOSE: Anthracycline induced cardiotoxicity is well known and its pathology is characterized by localized myocardial cell necrosis and myocardial fibrosis. The variability in QT interval duration amongst the different leads of the standard 12-lead ECG(QT dispersion) is considered to reflect inhomogenous repolarization of the myocardium. The aim of this study was to assess the effects of anthracycline on cardiac electrophysiology, with special emphasis on dispersion of QT interval and its relation to cumulative doses. METHODS: Heart rate-corrected QT interval(QTc) and QT dispersion(QTd) were measured in standard 12-lead ECG in 34 cancer patients and compared with those of normal control. RESULTS: QTc was increased in cancer patients(462.2+/-36.0 msec vs 447.0+/-19.7 msec) but QTd was not different between the cancer patients and normal control as a whole(40.8+/-12.5 msec vs 36.6+/-9.2 msec). But in the 5-10 year age group, QTd was increased in cancer patients in comparison with that of age matched control(44.1+/-14.8 msec vs 34.0+/-9.7 msec). Also QTc in the 5-10 year age group, but not in the 11-15 year age group, was increased in cancer patients in comparison with that of age matched control(478.0+/-40.8 msec vs 446.5+/-20.9 msec). QTc and QTd were not different according to the cumulative doses of anthracycline in the cancer patients. Left ventricular systolic function was found normal in all cancer patients by echocardiographic examination. CONCLUSION: In the absence of a significant modification of echocardiographic parameters, increased inhomogeneity of ventricular repolarization could be an early marker of anthracycline cardiotoxicity. The changes of repolarization parameters were significant only in the younger age group and were not significant according to the cumulative doses. Anthracycline seemed to induce cardiotoxity from the small dose and more significantly in the younger heart.