Tumor necrosis factor-alpha (TNF-alpha) has been implicated in the pathogenesis of congestive heart failure and may be associated with an increase in mortality. A recent in vitro study showed that amiodarone decreases TNF-alpha production by human blood mononuclear cells in response to lipopolysaccharide. However, no previous clinical studies have determined the effect of chronic amiodarone therapy on TNF-alpha levels. Thus, the purpose of this study was to determine whether amiodarone affects TNF-alpha levels in patients with ischemic and nonischemic cardiomyopathy. TNF-alpha levels were analyzed by an enzyme-linked immunoassay using plasma samples at baseline, 1, and 2 years of follow-up in New York Heart Association class III patients (n = 40 in each of the placebo and amiodarone groups, mean ejection fraction 0.25+/-0.09) who were randomized in the Congestive Heart Failure-Survival Trial of Antiarrhythmic Therapy, a multicenter, double-blind, placebo-controlled study in which the effect of amiodarone on survival was investigated. TNF-alpha levels were elevated in both groups of patients at baseline, 6.6+/-3.1 and 7.7+/-5.3 pg/ml in the amiodarone and placebo groups, respectively (p = 0.3). There were no significant differences in demographic or clinical variables between the 2 groups. Amiodarone treatment was associated with a significant increase in TNF-alpha levels in patients with ischemic cardiomyopathy, 12.7+/-12.5 and 6.8+/-3.7 pg/ml in the amiodarone and placebo groups, respectively (p = 0.03) at 1 year. No change in TNF-alpha levels was observed in patients with nonischemic cardiomyopathy. In contrast to the in vitro data, amiodarone treatment is associated with an increase in TNF-alpha levels in patients with ischemic cardiomyopathy. This increase is not associated with an adverse effect on survival.