CORRESPONDENCE: LETTER TO THE EDITOR
Carvedilol for Anthracycline Cardiomyopathy Prevention
Fernando Florenzano, MD* and
Pamela Salman, MD
* Department of Medicine, University of Chile, Av Salvador 486, Santiago, Region Metropolitana, Chile (Email: fflorenz{at}med.uchile.cl).
Kalay et al. (1), in a population of apparently unselected patients receiving their first 6 cycles of anthracyclines, found in their control group a high incidence of functional cardiomyopathy: 24% of their patients had at the final examination an ejection fraction of 50% or less. This incidence of cardiac dysfunction is higher than the expected one for patients beginning their exposure to anthracyclines (2); this must be clearly explained, because it is the base of the suggested treatment effect: only one patient of the carvedilol group developed functional cardiomyopathy. The only risk factor for cardiomyopathy development that is apparently present in this relatively young population is a high accumulated dose, with a mean of 513.6 mg/m2 for adriamycin users and of 770.4 mg/m2 for epirubicin users, in the control group. The carvedilol-treated group received about the same mean doses.
Unfortunately, the investigators do not report the standard deviation of the total doses administered. If there is a large dispersion of data, the "nonsignificant" Student t test reported for the comparison of total doses between groups loses confidence. Large dispersion of data in this regard may imply different distribution of total doses, with consequent different risks to both groups, independently of the influence of treatment on cardiac prognosis. When one is trying to reach conclusions with a small set of data, meticulous presentation of both data and appropriate statistics is mandatory.
Also, the total dose of adriamycin and epirubicin appears unusually high in a population naïve to previous anthracycline exposure: we calculate cycles of about 87 mg/m2 for adriamycin users and about 130 mg/m2 for epirubicin users, which are not the usual doses for breast cancer or lymphoma treatment. This also requires clarification.
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References
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1. Kalay N, Basar E, Ozdogru I, et al. Protective effects of carvedilol against anthracycline-induced cardiomyopathy J Am Coll Cardiol 2006;48:2258-2262.[Abstract/Free Full Text]2. Swain MS, Whaley FS, Ewer MS. Congestive heart failure in patients treated with doxorubicin Cancer 2003;97:2869-2879.[CrossRef][Web of Science][Medline]
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