Prediction of infarct severity from triiodothyronine levels in patients with ST-elevation myocardial infarction

Abstract

Background/AimsThe aim of the present study was to evaluate the relationship between thyroid hormone levels and infarct severity in patients with ST-elevation myocardial infarction (STEMI).Methods We retrospectively reviewed thyroid hormone levels, infarct severity, and the extent of transmurality in 40 STEMI patients evaluated via contrast-enhanced cardiac magnetic resonance imaging.ResultsThe high triiodothyronine (T3) group (≥ 68.3 ng/dL) exhibited a significantly higher extent of transmural involvement (late transmural enhancement > 75% after administration of gadolinium contrast agent) than did the low T3 group (60% vs. 15%; p = 0.003). However, no significant difference was evident between the high- and low-thyroid-stimulating hormone/free thyroxine (FT4) groups. When the T3 cutoff level was set to 68.3 ng/dL using a receiver operating characteristic curve, the sensitivity was 80% and the specificity 68% in terms of differentiating between those with and without transmural involvement. Upon logistic regression analysis, high T3 level was an independent predictor of transmural involvement after adjustment for the presence of diabetes mellitus (DM) and the use of glycoprotein IIb/IIIa inhibitors (odds ratio, 40.62; 95% confidence interval, 3.29 to 502; p = 0.004).ConclusionsThe T3 level predicted transmural involvement that was independent of glycoprotein IIb/IIIa inhibitor use and DM positivity.

The role of thyroid hormones in acute coronary syndromes: Prognostic value of alterations in thyroid hormones

“…Lymvaios et al also reported a strong association of low T3 with impaired ventricular function among AMI patients, concluding that T3 levels may represent a predictor of ventricular functional recovery . Interestingly, the findings of another study exhibited that the extent of transmural involvement in patients with STEMI, assessed by cardiac magnetic resonance imaging 40 days after the event, is strongly associated with T3 levels . In this retrospective and small‐sized study, the group with high/normal T3 levels had a significantly greater extent of transmural involvement than the low‐T3 group, which presented a significantly larger myocardial area at risk, thus a greater extent of ischemia and an increased myocardial salvage index .…”

“…Interestingly, the findings of another study exhibited that the extent of transmural involvement in patients with STEMI, assessed by cardiac magnetic resonance imaging 40 days after the event, is strongly associated with T3 levels . In this retrospective and small‐sized study, the group with high/normal T3 levels had a significantly greater extent of transmural involvement than the low‐T3 group, which presented a significantly larger myocardial area at risk, thus a greater extent of ischemia and an increased myocardial salvage index . The authors concluded that the transient low T3 state during AMI is associated with lower transmurality, suggesting a protective role of the low T3 syndrome.…”

“…The exact prevalence of the low T3 syndrome among patients suffering an ACS seems not to be clearly defined yet. A wide range from 5% to 35% has been reported in literature, and this could be attributed to differences in study populations between the conducted studies . However, the syndrome seems to occur more frequently in STEMI compared with NSTEMI patients, possibly because of their poorer early prognosis and the pathophysiologic features of the occlusive thrombus resulting in more myocardium at stake …”

“…Different interpretations of the low T3 syndrome in literature reflect our limited understanding of the pathophysiology of the syndrome. Although low TH plasma concentrations have been linked to adverse prognosis, it has been proposed that this transient low T3 status during an AMI may be actually cardioprotective, by reducing energy expenditure, heart rate, and oxygen consumption during the ischemic stress . Moreover, it has been also suggested that down‐regulation of the thyroid hormone system in patients suffering from myocardial ischemia, even prior to AMI manifestation, might be beneficial, in an attempt to reduce myocardial oxygen demands .…”

Role of Thyroid Hormones in Different Aspects of Cardiovascular System

“…A high T3 level was an independent predictor of transmural involvement after adjustment for the presence of Diabetes Mellitus and the use of glycoprotein IIb/IIIa inhibitors [74].…”