Sick euthyroid syndrome is associated with poor prognosis in patients with ST segment elevation myocardial infarction undergoing primary percutaneous intervention.

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.