Prevalence of Subclinical Hypothyroidism in Acute Coronary Syndrome in Nondiabetics: Detailed Analysis from Consecutive 1100 Patients from Eastern India

BACKGROUND: The association between subclinical thyroid dysfunction (defined by no symptoms or clinical features of hypothyroidism but biochemically TSH level in the range of above 5 miu/ml but below 10 miu/ml with normal FT4 level) and Acute Coronary Syndrome (ACS) is not known so far. This study was done to calculate the prevalence of subclinical thyroid dysfunction in patients with ACS. METHODS: A retrospective chart review of 1100 consecutive patients was done who presented to Emergency Department with symptoms suggestive of ACS and admitted. They were later classified in 3 categories that includes Acute ST Elevated Myocardial Infarction (STEMI), Unstable Angina (UA), and Acute Non-ST Elevated Myocardial Infarction (NSTEMI). Thyroid function test (FT4, TSH) and antithyroid peroxidase (TPO) were done and evaluated properly. RESULTS: Of 1100 consecutive patients 168 (15.27%) patients had the biochemical features of subclinical thyroid dysfunction. These 168 patients include 60 STEMI, 66 NSTEMI, and 42 Unstable Angina patients. There were no statistically significant differences in terms of left ventricular ejection fraction (LVEF) and catheterisation results considering thyroid dysfunction. CONCLUSIONS: Subclinical thyroid dysfunction is quite prevalent in ACS patients. There are no significant associations between STEMI, Unstable Angina, or NSTEMI patients in terms of thyroid dysfunction neither in single vessel versus multivessel disease involvement. The causative role and outcomes of treatment are still uncertain and need further follow-up.