Randomized, double-blind. Randomization was stratified by total anthracycline dose, follow-up time from treatment, and age at time of treatment. All patients received the following baseline tests: Maximal Cardiac Index (MCI) on cycle ergometry; echocardiogram/Doppler determined left ventricular end systolic wall stress (ESWS); gated nuclear angiography (GNA) to determine left ventricular ejection fraction; Holter monitoring for 24 hour ECG monitoring. Patients were randomized to either enalapril or placebo. Follow-up visits were conducted to ensure compliance and screen for side effects. MCI and ESWS were measured twice yearly, while all four tests were repeated at the conclusion of the trial, after four to five years of treatment. The primary outcome variables were the rate of decline in MCI and the rate of increase in ESWS. Secondary outcomes were the change in left ventricular ejection fraction and the incidence of arrhythmias. A second aim of the study was to develop an algorithm to determine indications for enalapril use if the study succeeded in showing a treatment effect. This required modeling the probability of cardiac dysfunction given patient characteristics at treatment, treatment type, cardiac status during treatment and at follow-up, and the development of cost effectiveness and medical decision making models testing the proposed algorithm.