Late cardiomyopathy in childhood acute myeloid leukemia survivors: a study from the L.E.A. program

Late cardiomyopathy in childhood acute myeloid leukemia survivors: a study from the L.E. A. program Prognosis of pediatric acute myeloid leukemia (AML) has improved significantly over the past two decades with survival rates now approaching 70%. 1 Therapy consists of a limited number of intensive chemotherapy courses mainly based on cytarabine and anthracycline. 2,3 Many pediatric late anthracycline cardiotoxicity studies have concerned heterogeneous diagnostic groups. Moreover, single childhood cancer studies were mainly conducted in acute lym-phoblastic leukemia, whereas the highest doses of anthra-cycline are given in children with AML. 4-6 We report here a prospective multi-centric study of late cardiotoxicity in 185 patients surviving childhood AML. All were treated after 1989 in French clinical trials using intensive chemotherapy alone or chemotherapy and allogeneic hematopoietic stem cell transplantation (HSCT). L.E. A. (Leucemie Enfant & Adolescent) is a French prospective long-term follow-up program involving all childhood acute leukemia survivors treated in the participating centers since 1980. Details of the programm are provided elsewhere. 7 As of 31 December 2011, 282 childhood AML survivors fulfilled the L.E. A. inclusion criteria and 218 (77.3%) of them agreed to participate. Among these 218, 185 were treated according to one of the 6 multicenter trial protocols ongoing in France after January 1989. All 185 had serial echocardiographic examination as part of their L.E. A. program, and all were included in the present study. All provided written informed consent. Cardiotoxicity was defined by either clinical symptoms of congestive heart failure or by an abnormal echocardiographic left ventricular function. Left ventricular function was considered abnormal when the shortening fraction (SF) was less than 28% or when the left ventricular ejection fraction (LVEF) was less than 55% on 2D echocardiography. 8-10 Cardiotoxicity was classified as late when it started or persisted beyond one year after the completion of first-line treatment. 9 Cumulative anthracycline doses used in each trial are described in the Online Supplementary Table S1, as well as the doxorubicin-equivalent doses using conversion factors of 0.83, 4.0 and 5.0 for daunorubicin, mitoxantrone and idarubicin, respectively. 10,11 Assessment of health status, long-term late effects on health-related quality of life (QoL), and statistical analysis are described in the Online Supplementary Appendix. Characteristics of the study cohort are summarized in Table 1. Median age at the time of AML diagnosis and median follow-up duration to last cardiac evaluation were 6.53 and 9.5 years, respectively. Thirty-seven patients had a history of relapse. Median cumulative anthracycline dose was 372 mg/m² (Online Supplementary Figure S1). Ninety-nine patients were treated by chemotherapy alone, whereas the other 86 patients also received HSCT (57 in first remission, 25 in second remission, and 4 in more advanced disease). Thirty children received total body irradiation (TBI), but only 10 among the 57 transplanted in first remission did so. Median number of echographic evaluations was 3 per patient. Subclinical cardiotoxicity (SCC) was observed in 23 of 185 patients (12.4%) at least once during their follow-up program. Median time from AML diagnosis to SCC detection was 4.40 years. In these 23 patients, the median value of the worst SF was 27% and the median value of the worst LVEF was 52. Only 3 of 23 patients had a worse SF value of less than 25% (2 had 20%; 1 had 24%). Six of 23 received anti-congestive therapy and none had cardiac transplantation. Five of those receiving anti-congestive therapy were still being treated at time of last evaluation, and 4 had more than 28% SF and more than 55% LVEF. Seventeen patients never received treatment: 11 had spontaneous improvement with more than 28% SF and more than 55% LVEF at last evaluation. Finally, at last cardiac evaluation, only 8 patients had an abnormal left ventricular function. Cumulative incidence (CI) of cardiotoxicity, estimated by the Kaplan-Meier method was 16% and 27% at 10 and 15 years, respectively (Figure 1A). CI of anti-conges-tive treatment at the same follow-up times was 5% and 7%. The risk of developing cardiotoxicity depended on a previous history of relapse and on the cumulative anthracy-cline dose. At ten years from diagnosis, CI was 35% versus 11% in patients with or without history of relapse (P=0.02) (Figure 1B). Among 148 patients without any history of relapse, 10-year CI of cardiotoxicity was 14% in 97 patients treated with chemotherapy alone versus 8% in 51 patients who underwent HSCT in first remission (NS, Figure 1C). In transplanted children, the risk was not modified by either a grade 2-4 acute or an extensive chronic graft-versus-host disease. The CI of anti-congestive treatment in these 148 patients who never experienced relapse was 3% at ten and