Thyroid Dysfunction in Acute Coronary Syndrome and its Relation to Morbidity and Mortality

Background: Thyroid hormones have important effects on the cardiovascular system through direct and indirect mechanisms. A typical pattern of altered thyroid hormone metabolism characterized by low T3 circulating levels has been described in patients with acute myocardial infarction, heart failure and in adults and children after cardiopulmonary bypass. We tried to evaluate the prevalence of thyroid dysfunction in patients with acute coronary syndrome (ACS) and to study the impact of these dysfunctions on morbidity and mortality among those subjects. Subjects and methods: A prospective cohort study conducting on 196 acute coronary syndrome patients divided into 98 patients with STEMI and 98 patients with NSTEMI or unstable angina (UA). They were subjected to full history and clinical examination and routine investigations, ECG, cardiac enzyme and APPACHE II score in addition to estimation of TSH, FT4 and FT3 using enzyme linked immunosorbent assay (ELISA). Results: The prevalence of thyroid dysfunctions in acute coronary syndrome were 23% from which the most prevalent thyroid dysfunction in this study is Euthyroid Sick syndrome (ESS) (68.9%) followed by Subclinical Hypothyroidism (24.5%) then Subclinical Hyperthyroidism (6.6%). Thyroid dysfunction in acute coronary syndrome increases relative risk of occurrence of shock, arrhythmia and reinfarction by 6.04, 2.05 and 1.67 fold respectively than euthyroid patients. Thyroid dysfunction in STEMI group increase relative risk of arrhythmia, reinfarction and Shock by 2.25, 2.4 and 8.3 fold respectively than euthyroid patients while it increases the arrhythmia and shock by 1.5 and 1.4 fold respectively with no impact on reinfarction in NSTEMI & unstable angina group. Significant increase in APACHE II score >14 and mortality in patients with thyroid dysfunction as compared to euthyroid patients. Thyroid dysfunction in acute coronary syndrome increase relative risk of death by 5.49 fold than euthyroid patients. Morbidity and mortality were significantly increased in Euthyroid sick syndrome (low T3 syndrome) in STEMI group with no significant difference in this respect in NSTEMI & unstable angina group. Conclusion: The prevalence of thyroid dysfunction in our cohort of ACS patients was 23%.most prevalent is ESS. UA, NSTEMI and STEMI patients were affected by ESS. ESS was significantly associated with all cause morbidity & mortality which was significant in STEMI group than NSTEMI & UA group.