A Low fT3 Level as a Prognostic Marker in Patients with Acute Myocardial Infarctions

Abstract

Objective To investigate the association between low free triiodothyronine (fT3) levels and the severity and prognosis of patients with acute myocardial infarction. Methods A total of 501 patients with acute myocardial infarctions were enrolled in our study. The circulating levels of thyroid hormones and clinical parameters were assayed. The patients were categorized into either the low fT3 group or the normal fT3 group according to the fT3 level on admission. All patients underwent a follow-up for 10±2 months for mortality from any cause and the occurrence of any adverse major cardiac events (MACE). Results There were 171 patients in the low fT3 group (fT3<3.5 pmol/L) and 330 patients in the normal fT3 group (! 3.5 pmol/L). During the follow-up period, 33 patients died (6.6%) and the overall survival rates were 86.0% and 97.3% in patients with a low fT3 level and a normal fT3 level, respectively. The rates of MACE were 66.7% and 45.5% in the patients with and those without low fT3 levels, respectively. Using a multivariable Cox proportional hazards model, the fT3 level was found to be the most important predictor of cumulative death and MACE (hazard ratio [HR] for death: 0.142, p<0.001 and HR for major adverse cardiac events: 0.748, p=0.007). A Kaplan-Meier analysis revealed that those patients with low fT3 levels had higher rates of MACE and death. Conclusion A low fT3 level, a common phenomenon in patients with acute myocardial infarctions, is a strong predictor of short-term and long-term poor prognoses in patients with acute myocardial infarctions.

Left ventricular function by speckle-tracking echocardiography in patients with low-T3 syndrome and acute myocardial infarction

“…The increased D3 activity converts fT3 into the inactive metabolite rT3, resulting in reduced T3 levels, which in turn affects contractile activity and energy metabolism [11]. Inflammation, hypoxia, and hemodynamic instability might also contribute to the decrease in T3 levels [12,13]. Low thyroid hormone state, particularly, low fT3 levels, is found in ischemic myocardial conditions, and may be a protective response against ischemic stress [14].…”

“…Blood samples were stored at 18-25 8C until a clot formed (after about 15-45 min), and serums were separated by centrifugation (1200 Â g, for 15 min), and were analyzed using the automated enzyme immunoassay analyzer AIA-2000 (Tosoh corporation, Japan). The reference intervals were as follows: 3.2-5.9 pmol/L for fT3, [9][10][11][12][13][14][15][16][17][18][19][20][21].07 pmol/L for fT4, 0.38-4.31 mU/L for TSH, and <3.2 kU/L for anti-TPO.…”

Role of Thyroid Hormones in Different Aspects of Cardiovascular System

“…The rates of MACEs were 66.7% and 45.5% in the patients with and those without low fT3 levels, respectively. The fT3 level was found to be the most important predictor of cumulative death and MACEs; and those patients with low fT3 levels had higher rates of MACEs and death [73].…”

Free Triiodothyronine Level Indicates the Degree of Myocardial Injury in Patients with Acute Myocardial Infarction

“…Patients were diagnosed to have MI based on the presence of chest pain, ST elevation on ECG, and Regional Wall Motion Abnormality on echocardiogram. For the above cross sectional study, sample size was calculated with a precision or absolute error (d) of 10% , SD-standard deviation of FT3 in MI, as obtained from a study by Wang Wen-Yao et al, as 0.47 [9] and standard normal variate Z which is 1.96 for p <0.05 to be 84 subjects and 5% nonresponders were added .Hence a total of 88 patients was obtained. The exclusion criteria were thyroid diseases history, therapy with amiodarone, thyroid hormone, glucocorticoids; interventional or surgical procedures performed within the last 3 months, patients who received radiographic contrast medium within 2 weeks before measurements, as these states were known to influence the parameters of the study.…”