OBJECTIVE: This study aimed to investigate thyroid hormone (TH) status and its 
relationship with myocardial function as well as clinical and biochemical 
parameters in stress cardiomyopathy (CMP).
METHODS: Forty-five patients with stress CMP (the patient group), 31 patients 
without stress CMP (the control II group), and 58 healthy subjects (the control 
I group) were included. Sick euthyroid syndrome (SES) was defined as low total 
triiodothyronine (T(3)) with normal TSH levels.
RESULTS: In the patient group at admission, prevalence of SES was 62.2%. 
Compared with the control I group, the patient group had a decrease in left 
ventricular ejection fraction (LVEF) and systolic blood pressure (BP) and an 
increase in troponin-I, CK-MB, and B-type natriuretic peptide (BNP) levels. 
Total T(3) levels were reduced, and anti-thyroid peroxidase antibody (anti-TPO 
Ab) positivity, C-reactive protein (CRP) and cortisol levels were elevated. 
Total T(3) levels were associated with acute physiology and chronic health 
evaluation II (APACHE II) score, LVEF, systolic BP, and cortisol levels in 
multivariate analysis. In the control II group, total T(3) levels were not 
associated with any variables. In the SES (n=28) and myocardial dysfunction 
(MDys, n=27) subgroups, increased APACHE II score and BNP levels as well as 
decreased LVEF and systolic BP were significant. Total T(3) levels were reduced, 
and CRP, cortisol and catecholamines levels were elevated. In the MDys subgroup, 
anti-TPO Ab positivity and titer were increased.
CONCLUSION: These results suggest that total T(3) levels may be associated with 
myocardial contractility, clinical severity, and cortisol levels. Thyroid 
autoimmunity may influence myocardial contractility in stress CMP.