RESUMEN
Objectives: This study aimed to examine possible associations between previously undiagnosed subclinical hypothyroidism and short-term outcomes and mortality in a sample of Iraqi patients undergoing primary percutaneous coronary intervention for ST-segment elevation myocardial infarction. Design: This is a prospective observational cohort study. Setting: The study was conducted in a single tertiary referral centre in Baghdad, Iraq. Participants: Thyroid-stimulating hormone and free T4 levels were measured in 257 patients hospitalised with STelevation myocardial infarction who underwent primary percutaneous coronary intervention between January 2020 and March 2022. Main outcome measures: Adverse cardiovascular and renal events during hospitalisation and 30-day mortality were observed. Results: Previously undiagnosed subclinical hypothyroidism was detected in 36/257 (14%) ST-elevation myocardial infarction patients and observed more commonly in females than males. Patients with subclinical hypothyroidism had significantly worse short-term outcomes, including higher rates of suboptimal TIMI Flow (< III) (p =0.014), left ventricular ejection fraction ≤ 40% (p=0.035), Killip class >I (p=0.042), cardiogenic shock (p =0.016), cardiac arrest in the hospital (p= 0.01), and acute kidney injury (p= 0.044). Additionally, 30-day mortality was significantly higher in patients with subclinical hypothyroidism (p= 0.029). Conclusion: Subclinical hypothyroidism previously undiagnosed and untreated had a significant association with adverse short-term outcomes and higher short-term mortality within 30 days compared to euthyroid patients undergoing primary percutaneous coronary intervention. Routine thyroid function testing during these patients' hospitalisation may be warranted.