BACKGROUND: Concomitant thyroid and heart disease are frequently encountered in 
clinical practice. There are many studies evaluating thyroid function in acute 
and critical conditions. Information on thyroid dysfunction in ST-segment 
elevation myocardial infarction (STEMI) is limited; its correlation with short 
and long-term outcome is not fully known.
METHODS: Four hundred and fifty seven patients diagnosed with STEMI in our 
emergency department were included in the study. Patients were divided into two 
groups: patients with normal thyroid function (euthyroid) and patients with 
thyroid dysfunction. STEMI was diagnosed with 12 derivation surface 
electrocardiogram. Thyroid hormone levels (TSH, free T3 and free T4) were 
measured. Patients with other acute coronary syndromes and endocrine pathologies 
except diabetes mellitus were excluded. Two patient groups were compared in 
terms of in-hospital and long-term outcome.
RESULTS: Out of 457, 72 (15%) patients with thyroid dysfunction were detected. 
The other patients were euthyroid and constituted the control group. In-hospital 
cardiogenic shock (15% vs. 3% in the control group; p < 0.01) and death (7% vs. 
1% in the control group; p < 0.01) were more frequently observed in the thyroid 
dysfunction group. In the subgroup analysis, it was observed that patients with 
sick euthyroid syndrome have the poorest outcome. Other markers for poor outcome 
were anemia and renal failure.
CONCLUSIONS: Thyroid dysfunction, particularly sick euthyroid syndrome, was 
found to be related to in-hospital and long term mortality in patients with 
STEMI undergoing primary percutaneous intervention.