Triiodothyronine levels for risk stratification of patients with chronic heart failure

Purpose We sought to explore the use of triiodothyronine (T3) concentrations as an adjunct to clinical and functional parameters when estimating prognosis in patients with chronic heart failure. Methods We enrolled 281 patients with postischemic (n = 153) or nonischemic (n = 128) dilated cardiomyopathy. Total and free T3 concentrations, and traditional clinical and functional cardiac parameters, were measured 2 to 5 days after hospital admission. A multivariate model was utilized to predict all-cause and cardiac mortality. Results All-cause mortality was 23% (n = 64) after a mean (±SD) of 12 ± 7 months of follow-up; 47 (73%) of the patients died from cardiac causes. The mean ejection fraction was lower in those patients who died than in those who survived (26% ± 8% vs. 31% ± 8%, P< 0.001), as were levels of total T3 (1.0 ± 0.4 nmol/L vs. 1.3 ± 0.3 nmol/L, P< 0.001) and free T3 (3.2 ± 1.4 pmol/L vs. 3.7 ± 1.0 pmol/L, P< 0.001). In a multivariate model, ejection fraction (odds ratio [OR] = 2.0 per 10% decrease; 95% confidence interval [CI]: 1.4 to 2.8 per 10% decrease; P< 0.001) and total T3 level (OR = 0.3 per 1-nmol/L increase; 95% CI: 0.1 to 0.5 per 1-nmol/L increase; P< 0.001) were the only independent predictors of all-cause mortality. In an alternative model using free T3 levels, ejection fraction (OR = 1.9; 95% CI: 1.4 to 2.7; P< 0.001) and free T3 level (OR = 0.6 per 1 pmol/L; 95% CI: 0.5 to 0.8 per 1 pmol/L; P<0.02) were associated with all-cause mortality. When we considered cardiac mortality alone, male sex (OR = 3.5; 95% CI: 1.7 to 13; P< 0.04), ejection fraction (OR = 1.7; 95% CI: 1.2 to 2.5; P< 0.006), and total T3 level (OR = 0.3; 95% CI: 0.2 to 0.7; P< 0.002) were independent predictors with the multivariate model. Conclusion Low T3 levels are an independent predictor of mortality in patients with chronic heart failure, adding prognostic information to conventional clinical and functional cardiac parameters.