Introduction: Thyroid dysfunction is common affecting 510% of the adult population. Cardiovascular disease, including acute myocardial infarction (AMI), has been suggested as one of the adverse outcomes of thyroid disease. Furthermore, individuals with thyroid dysfunction at the time of AMI have worse outcomes. Despite this, there is scarce data on the prevalence of thyroid dysfunction in patients with AMI. We conducted a prospective observational multi-centre study to investigate the prevalence of and factors predicting thyroid dysfunction in patients with AMI.
Methods: Consecutive patients (n=1970) from five hospitals within the North-East of England with AMI (both STEMI and NSTEMI) between January 2015 and December 2016 were recruited. Thyroid function tests were evaluated on the first available sample between 124 hours of admission. Patients on medications affecting thyroid function were excluded from the analysis. The prevalence of thyroid dysfunction was calculated and logistic regression analysis performed to assess relationship with demographic, clinical and biochemical variables.
Results: The thyroid status of the 1809 patients were: 78.6% (n= 1422) euthyroid, 17.3% (n= 314) subclinical hypothyroidism (SCH), 1.2% subclinical hyperthyroidism, 2.7% (n=49) low T3 syndrome (LT3S), and overt hypothyroidism and hyperthyroidism 0.5% each. Predictors for SCH were increasing age with OR (Odds ratio (95% CI) of 1.02 (1.011.04); P=0.001, STEMI with OR 2.11 (1.522.93); P
Conclusion: Thyroid dysfunction is common in patients presenting with AMI particularly SCH that is present in 1 in 6. Furthermore, troponin rise is higher in SCH patients with AMI, independent of other factors, which may partly explain the increased morbidity and mortality observed in these patients. Interventional studies are necessary to evaluate if treatment post-AMI improves outcomes.