The Prevalence of Low T3 With Arrhythmia and Heart Failure in Patients With Acute Coronary Syndrome

Abstract

Aims:To investigate the prevalence of low T3 in patients with acute coronary syndrome (ACS). Methods: A total of 135 (44 female, 91 male) patients with the diagnosis of ACS hospitalized in coronary care unit were enrolled in the study. Results: The prevalence of low TT3 in ACS was 36%. The probability of acute complications in patients with low TT3 was 1.81 times that of patients with normal TT3 (95% confidence interval, 1.24 -2.67). TT3 and FT3 values were lower in the patients with acute complications than in those without acute complications (P Ͻ 0.001 and P ϭ 0.011, respectively). TT3 and FT3 values were lower in patients with heart failure than in patients without heart failure (P Ͻ 0.001 and P ϭ 0.003, respectively). The relative risk of heart failure in patients with low TT3 versus in those with normal TT3 was 2.78 with 95% confidence interval 1.52 to 5.07. Average TT3 values of the patients with arrhythmia and without arrhythmia were similar (P ϭ 0.032). There was no difference in terms of occurrence of arrhythmia in ACS patients with low TT3 and with normal TT3 (P ϭ 0.992). Conclusions: A low T3 in ACS was related to complications. Low T3 in ACS might be a factor, which protects against arrhythmia but predisposes to heart failure.Key Words: acute coronary syndrome, low t3, nonthyroidal illness, heart failure, arrhythmia (The Endocrinologist 2010;20: 23-26) N onthyroidal illness (NTI) refers to a group of changes in serum thyroid hormones, and TSH in patients with serious nonthyroidal diseases, including infection, inflammation, starvation, malignancy, trauma, burns, major surgical operations, psychosis, stroke, and acute coronary syndrome (ACS). 1-4 The most common and earliest alteration is inhibition of T4 -T3 conversion, which leads to low T3 serum levels. This is thought to be related to the inhibition of type 1 5Јdeiodinase enzyme action by a cytokine, such as tumor necrosis factor, released by inflammatory cells. Several drugs also inhibit this enzyme (eg, corticosteroids, propiltiouracil, iodinated contrast media, propranolol). As the illnesses becomes severe, serum TT4 and FT4 decrease. Several factors are involved in this decrease. Low thyroid binding globulin (nephrotic syndrome, liver disease) and high free fatty acids, which interfere with T4 binding to thyroid binding globulin. This, in turn, causes low TSH, and T4 decreases again, establishing a new equilibrium. TSH may also be inhibited by cytokines, dopamine, and corticosteroids. 4 The magnitude of the thyroid hormone alteration correlates with the severity of the disease with the lowest T3 and T4 values associated with decreased survival. 2,5 Recent studies show that low T3 is associated with increased mortality in patients with serious hearth disorders, and is an independent predictor of mortality in hospitalized cardiac patients. 6 We investigated the prevalence of patients with low T3 in the ACS and its subtypes (unstable angina pectoris ͓USAP͔, myocardial infarction with ST-elevation ͓STEMI͔, and myocardial infarction with non-ST-...

Prognostic implications of thyroid hormone alterations in acute coronary syndrome–A systematic review

“…Change in the serum thyroid hormone profile level has been depicted in various non-thyroidal illness, 17 , 18 , 19 Abnormal thyroid status increases the risk of coronary artery disease and cardiovascular mortality, 20 alterations in TH plasma concentrations during a variety of acute and chronic illnesses in patients with no known intrinsic thyroid disease are described by various terms in literature, such as “euthyroid sick syndrome”, “nonthyroidal illness syndrome,” and “low T3 syndrome", 4 , 2 It is known that changes in thyroid hormone develop within hours in case of acute non-thyroidal diseases. 20 It is most frequently characterized by low T3 or fT3, elevated rT3, normal T4 and TSH. 21 , 22 , 23 , 24 , 25 Low level of fT3 is also associated with greater LV diameters and LV end-diastolic volume, and decreased systolic LV function.…”

Predictive Value of Free Triiodothyronine in Patients with Acute Coronary Syndrome Undergoing Percutaneous Coronary Intervention

“…Thyroid hormone metabolism disorders increase the risk of CAD and cardiovascular death, therefore evaluation of FT3 levels may benefit to identify patients who are susceptible to cardiovascular disease [ 16 , 17 , 18 ]. Therefore, assessment of FT3 levels has important clinical significance for risk stratification and individualized treatment of such patients.…”