Correspondence Letter by Rassi et al Regarding Article, “-Blocker Therapy and Mortality of Patients With Chagas Cardiomyopathy: A Subanalysis of the REMADHE Prospective Trial” To the Editor:

In a retrospective, nonrandomized subanalysis of the single-center REMADHE trial, Issa et al1 suggest that -blockers may improve survival among patients with heart failure of chagasic etiology and that physicians should not hesitate to prescribe them. However, this beneficial effect may have arisen due to chance (P value0.05) because of a small sample (only 68 patients, 24 on and 44 off -blockers) or to differences in baseline characteristics (eg, more males and fewer patients using angiotensin-converting enzyme inhibitors and spironolactone in the non--blocker group), because -blocker use was not determined randomly. Moreover, the baseline data regarding other important prognostic markers (eg, New York Heart Association class, cardiomegaly, and non-sustained ventricular tachycardia [NSVT]) were not provided. Of note, when the sample size is small, even nonstatistically significant differences in baseline characteristics may still be large enough to exert a substantial effec