Subclinical cardiac dysfunction and exercise performance in childhood cancer survivors

BACKGROUND: Although anthracycline cardiotoxicity is clearly related to the cumulative dose administered, subclinical cardiac dysfunction has been reported across a wide range of treatment regimens, and its clinical significance is still unclear. Purpose of this study is to investigate by exercise echocardiography for subclinical cardiac dysfunction in survivors of pediatric cancer treated with low-moderate anthracycline doses, and to evaluate whether it may alter the response of the cardiovascular system to dynamic exercise. PROCEDURE: Post-exercise left ventricular end-systolic wall stress (ESS), left ventricular posterior wall dimension and percent thickening at end systole, and cardiopulmonary exercise test-derived indexes of cardiac function were examined in 55 apparently healthy patients (mean age 13.5 ± 2.9 years, median anthracycline cumulative dose 240 mg/m(2)) and in 63 controls. RESULTS: Subclinical cardiac dysfunction was identified in 17 patients (30%) presenting reduced left ventricular posterior wall dimension or percent thickening, or increased values of left ventricular ESS as compared to controls (group A), while the remaining patients formed group B. Reduced oxygen consumption at peak exercise in both groups of patients was the only cardiopulmonary exercise test variable resulting significantly different between patients and controls: no differences were found among the groups of patients. CONCLUSIONS: Our results confirm that even patients treated with a median anthracycline dose of 240 mg/m(2) (range 100-490) are at considerable risk of exhibiting subclinical cardiac dysfunction that, however, does not seem to alter the physiologic response of the cardiovascular system to dynamic exercise.