Although low levels of free triiodothyronine and high levels of brain 
natriuretic peptide have been shown as independent predictors of death in 
chronic heart failure patients, few studies have compared their prognostic 
values. The aim of this prospective study was to measure free triiodothyronine 
and brain natriuretic peptide levels and to compare their prognostic values 
among such patients.A total of 334 patients (mean age, 62 ± 13 yr; 218 men) with 
ischemic and nonischemic dilated cardiomyopathy were included in the study. The 
primary endpoint was a major cardiac event.During the follow-up period, 92 
patients (28%) experienced a major cardiac event. Mean free triiodothyronine 
levels were lower and median brain natriuretic peptide levels were higher in 
patients with major cardiac events than in those without. A significant negative 
correlation was found between free triiodothyronine and brain natriuretic 
peptide levels. Receiver operating characteristic curve analysis showed that the 
predictive cutoff values were < 2.12 pg/mL for free triiodothyronine and > 686 
pg/mL for brain natriuretic peptide. Cumulative survival was significantly lower 
among patients with free triiodothyronine < 2.12 pg/mL and among patients with 
brain natriuretic peptide > 686 pg/mL. In multivariate analysis, the significant 
independent predictors of major cardiac events were age, free triiodothyronine, 
and brain natriuretic peptide.In the present study, free triiodothyronine and 
brain natriuretic peptide had similar prognostic values for predicting long-term 
prognosis in chronic heart failure patients. These results also suggested that 
combining these biomarkers may provide an important risk indicator for patients 
with heart failure.