Cardiac toxicity after anthracycline chemotherapy in childhood

The clinical use of anthracyclines, a family of chemotherapeutic agents with efficacy against many solid tumors and leukemias is limited by unique cumulative dose-limiting cardiotoxicity. Overt heart failure occurs in 4.5% to 7% of patients treated with anthracyclines and the incidence of cardiac function abnormalities increases with the time. Anthracycline-induced congestive heart failure is usually due to permanent changes in the myocardium, changes most consistent with the contractile failure of cardiomyopathy. Although the causes of anthracycline-induced cardiotoxicity are probably many, a large body of evidence points to free-radical-mediated myocyte damage. The risk of developing cardiac heart failure is modified by the presence of certain risk factors that reduce cardiac tolerance to anthracyclines. Age and female gender seem to have an important role in the anthracycline cardiotoxicity. This cardiotoxicity can be divided, on the base of when it started, into acute, subacute and progressive late, chronic form. Various invasive and non-invasive methods have been used to measure the extent of cardiac damage done. Depending on the sensitivity of the method employed, the proportion of hearts found to be damaged has varied widely. Attempts to ameliorate anthracycline cardiotoxicity have been directed toward: 1. decreasing myocardial concentrations of anthracyclines and their metabolites, 2. developing less cardiotoxic analogous, and 3. concurrently administering cardioprotectants to attenuate the effects of anthracyclines on the heart. Much progress has been made in terms of monitoring of clinical and subclinical anthracycline cardiotoxicity, finding alternative schedules, introducing special carriers of anthracyclines and using cardioprotecting agents. It is hoped that with all these effects and with results of ongoing and future trials, we will be able to reduce further or even eliminate anthracycline cardiotoxicity.