Cyclophosphamide cardiotoxicity in bone marrow transplantation: a prospective evaluation of new dosing regimens.

Cyclophosphamide (CY) cardiotoxicity may be a lethal complication of bone marrow transplantation. Previous echocardiographic studies have reported that left ventricular dysfunction due to CY occurs in over 50% of patients undergoing transplantation. To evaluate the cardiotoxicity of new dosing protocols that included twice-daily rather than once-daily CY, 44 bone marrow transplantation patients were prospectively evaluated with serial ECGs and echocardiograms. Twenty-six patients received a once-daily lower-dose protocol (mean total 87 +/- 11 mg/kg), and 18 patients received a twice-daily higher-dose (mean total 174 +/- 34 mg/kg) CY regimen. In the higher-dose CY group, significant reductions in summed ECG voltage (-20%) (P less than .01) and increases in left ventricular mass index (LVMI) (+10%) (P less than .05) were detected in the first week following therapy. These changes resolved by the third week following CY and were significantly greater than the changes noted in the lower-dose group. However, l...