Abstract
PurposeThyroid dysfunction in patients with cardiac disease is associated with worse outcomes. This study aimed to evaluate the prevalence and analyse predictors and outcomes of thyroid dysfunction in patients presenting with an acute myocardial infarction (AMI).MethodsA prospective multicentre observational study of patients recruited from six acute hospitals within the North of England. Consecutive patients without previous thyroid disease presenting with both ST-elevation AMI (STEMI) and non-ST-elevation AMI (NSTEMI) were recruited to the Thyroxine in Acute Myocardial Infarction 1 (ThyrAMI-1) cohort study between December 2014 and 2016. Thyroid profile, standard biochemistry measurements and demographic information were obtained within 12 h of admission to hospital. Multivariable logistic regression analyses were performed to assess the predictors of thyroid dysfunction and Cox proportional hazards analyses were utilised to compare all-cause mortality by categories of thyroid dysfunction up to June 2019.ResultsOf the 1802 participants analysed, 1440 (79.9%) were euthyroid, 312 (17.3%) had subclinical hypothyroidism (SCH), 22 (1.2%) had subclinical hyperthyroidism (SHyper) and 25 (1.3%) had low T3 syndrome (LT3S). Predictors for SCH were increasing age, female sex, higher thyroid peroxidase antibody (TPOAb) levels, higher serum creatinine levels and early morning sampling time (between 00:01–06:00 h). The predictors of SHyper were lower body mass index and afternoon sampling time (between 12:01 and 18:00 h). Predictors of LT3S were increasing age, higher creatinine levels and presence of previous ischaemic heart disease. Compared to the euthyroid group, patients with LT3S had higher all-cause mortality; adjusted hazard ratio (95% CI) of 2.02 (1.03–3.95), p = 0.04, whereas those with SCH and SHyper did not exhibit significantly increased mortality; adjusted hazard ratios (95% CI) of 1.05 (0.74–1.49), p = 0.79 and 0.27 (0.04–1.95), p = 0.19, respectively.ConclusionsThyroid dysfunction is common in AMI patients on admission to hospital and our data provide an understanding regarding which factors might influence thyroid dysfunction in these patients. Furthermore, the negative association between LT3S and increased mortality post-AMI has once again been highlighted by this study. More research is required to assess if treatment of thyroid dysfunction improves clinical outcomes.
Highlights
Thyroid dysfunction is common and can affect between 10–15% of the adult population [1]
The proportion of subclinical hypothyroidism (SCH) patients was highest in the time period 00:01–06:00 h, whereas the proportion of subclinical hyperthyroidism (SHyper) was highest between 18:01–12:00 h
This study confirms a high prevalence of thyroid dysfunction in acute myocardial infarction (AMI) patients
Summary
Thyroid dysfunction is common and can affect between 10–15% of the adult population [1] Both subclinical hypothyroidism (SCH) and subclinical hyperthyroidism (SHyper) are associated with higher risk of cardiovascular morbidity and mortality [2, 3]. Thyroid function tests are frequently requested both in community-living individuals and in hospitalised patients [10]. This understanding may help to prevent inappropriate diagnoses being made and unnecessary treatments being initiated [11]. We report here the results of our analyses of the prevalence, predictors and mortality outcomes of thyroid dysfunction in patients presenting with an AMI
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