The clinical features of fatal cyclophosphamide-induced cardiotoxicity in a conditioning regimen for allogeneic hematopoietic stem cell transplantation (allo-HSCT).

Cyclophosphamide (CY) cardiotoxicity induces a rare lethal complication associated with its use. The minimum dose for cardiac toxicity is still not known, although there are no reports of CY toxicity at doses of less than 100 mg/kg. There are few studies of CY cardiotoxicity that included a large number of patients who received high-dose CY for conditioning for allogeneic stem cell transplant (allo-HSCT). To elucidate the clinical course, complications, true incidence, and risk factors, the cardiac events of 811 patients who received more than a total of 100 mg/kg of CY as conditioning for allo-HSCT were analyzed. Twelve of 811 recipients (1.5 %) developed fatal cardiac failure induced by CY at a median of 4 (range 2-8) days after the first administration of CY. Regarding the dose of CY, 8.5, 1.2, and 0 % of the patients developed cardiac failure among the patients treated with a total of 200, 120, and 100 mg/kg CY, respectively. On echocardiography, the E/A ratio shows diastolic dysfunction but not the ejection fraction changed in the early course. Moreover, a short time to the first symptom after the administration of CY tended to be associated with early death (p = 0.09). Eleven patients died from progressive acute cardiac failure at day 7 (5-30) after the first administration of CY, and only one patient survived. In summary, fatal CY cardiotoxicity with allo-HSCT is a rare complication, but it is associated with high mortality. The possibility of CY-induced cardiotoxicity must be considered early after the administration of CY.