Functional monitoring of anthracycline cardiotoxicity: a prospective, blinded, long-term observational study of outcome in 120 patients.

BACKGROUND: With increasing doses the highly tumoricidal anthracycline drugs cause heart damage. Based on empirical drug limitations about 10-15% of patients will develop congestive heart failure (CHF) with a mortality of -50% within 2 years on digitalo-diuretic therapy alone. To avoid CHF there is a consensus recommendation that cardiac function should be monitored in close connection with anthracycline administration. As no prospective studies in a larger series have been performed, these recommendations are based on retrospective data on small numbers of patients. PATIENTS AND METHODS: In a prospective, blinded observational study 120 patients with advanced breast cancer were followed before, during, and a median 3 years after treatment with epirubicin. They had 604 serial radionuclide measurements of left ventricular ejection fraction (LVEF) that were stored without calculations except in patients who developed a well-defined CHF.
RESULTS: Anthracycline cardiotoxicity was closely correlated with the cumulative dose, with a great variability in individual susceptibility and a dramatic increase with advancing age. With a delayed onset of 3 months or more, epirubicin induced a threatening, slowly progressive deterioration of cardiac function continuing years after treatment. An actuarial estimation of 59% of the patients experienced a 25% relative reduction in LVEF 3 years after 850-1000 mg/m2 of epirubicin and 20% had deteriorated into a CHF. The patients did not spontaneously regain cardiac function whereas continued therapy with a circadian angiotensin-converting enzyme inhibitor for more than 3 months caused a remarkably potent and long-lasting recovery.
CONCLUSIONS: Due to the displaced cardiotoxic manifestation, functional monitoring in close connection with anthracycline administration appears to be a poorly effective method while later monitoring is essential. Current monitoring recommendations should therefore be revised.