Free triiodothyronine level indicates the degree of myocardial injury in patients with acute ST-elevation myocardial infarction / 中华医学杂志(英文版)

ABSTRACT

<p><b>BACKGROUND</b>Previous studies have suggested that hypothyroidism correlated with coronary heart diseases (CHD) mortality in long-term cohort, but whether the thyroid function status is associated with myocardial injury in acute ST-elevation myocardial infarction (STEMI) has not been investigated sufficiently.</p><p><b>METHODS</b>Five hundred and eighty-two hospitalized patients from January 2010 to December 2011, with the diagnosis of STEMI, were enrolled in this study. All patients underwent testing for thyroid function status, cardiac troponin I (cTnI), cardiac enzymes, C-reactive protein (CRP). We investigated the association between thyroid hormone levels and cardiac markers (creatine kinase-MB and cTnI), and thus evaluated the potential role of thyroid function status in predicting the myocardial injury.</p><p><b>RESULTS</b>There were 76 patients (13.06%) who had hypothyroidism including low-T3-syndrome (34 patients, 5.84%), subclinical hypothyroidism (28 patients, 4.81%) and clinical hypothyroidism (14 patients, 2.41%). After adjusting for conventional risk factors (age, gender, smoking, diabetes mellitus, dyslipidemia, hypertension), free triiodothyronine (FT3) was significantly and negatively correlated with log-CKMB (r = -0.244, P < 0.001) and log-cTnI (r = -0.290, P < 0.001), indicating that the lower thyroid hormone level correlates with the severer cardiac injury in STEMI patients. FT3 also had a moderate negative correlation with CRP (r = -0.475, P < 0.001), which might indicate that hypothyroidism may activate the inflammation response. No significant correlation was found between other thyroid parameters (TSH, FT4) and cardiac markers.</p><p><b>CONCLUSIONS</b>As the lower FT3 level correlates with higher level of cardiac markers and lower left ventricular ejection fraction (LVEF), the hypothyroidism may be a predictor for myocardial injury in STEMI. And these results may warrant further study to investigate whether reversing the hypothyroidism could benefit the STEMI patients.</p>