BACKGROUND: Abnormalities in thyroid function are frequent in patients with 
heart failure and are associated with increased mortality. However, the relation 
between thyroid hormone levels and echocardiographic parameters has not been 
investigated sufficiently.
AIM: The aims of this study were to investigate the correlations of thyroid 
hormone levels with echocardiographic parameters and to evaluate their 
associations with subsequent mortality in a group of patients with dilated 
cardiomyopathy (DCMP).
METHODS: Serum levels of thyroid hormones were measured in 111 consecutive 
patients with DCMP (35 female, 76 male, mean age: 62+/-12 years). All patients 
underwent echocardiographic examination and were followed-up for a period of 
12+/-8 months.
RESULTS: Twenty-three patients (21%) had abnormalities in thyroid function 
tests. Free triiodothyronine (fT3)/free thyroxine (fT4) ratio was significantly 
correlated with most of echocardiographic parameters, such as chamber diameters 
and ejection fraction. Sixteen patients (14%) died during the follow-up period; 
their fT3/fT4 ratio was significantly lower than the patients who survived 
(1.31+/-0.37 vs. 2.01+/-0.72, p<0.001). A fT3/fT4 ratio of <or=1.7 was 
associated with an increased risk of mortality (p<0.001), independent of other 
prognostic markers. Sensitivity, specificity, positive and negative predictivity 
of fT3/fT4 ratio <or=1.7 for cardiac mortality were 100%, 71%, 36% and 100%, 
respectively.
CONCLUSION: Determination of FT3/FT4 ratio may be a valuable and simple 
predictor for identification of patients with DCMP who are at high risk of 
subsequent mortality.