I am always reading that GPs/Endos. say that excess T3 can cause heart attacks/irregular beats and yet I also read that T3 protects the heart; who is right. Here is a small extract from one of the studies I have read:
Patients with heart disease frequently display a typical pattern of altered thyroid hormone metabolism, characterized by low circulating triiodothyronine (T3) levels in the absence of an intrinsic thyroid disease. This condition, variously known as the “low T3 syndrome” [1], the “nonthyroidal illness syndrome” [2], or the “euthy- roid sick syndrome” [3], is mainly due to the reduced peripheral conversion of T4 into T3 and has been observed in patients with myocardial infarction [4], heart failure [5], and after cardiac operations with and without cardiopulmonary bypass (CPB) [6, 7].
Accepted for publication Jan 14, 2014.
Address correspondence to Dr Cerillo, Operative Unit of Cardiac Surgery, “G. Pasquinucci” Hospital, “G. Monasterio” Foundation, Via Aurelia Sud 54100 Massa, Italy; e-mail: acerillo@yahoo.com.
! 2014 by The Society of Thoracic Surgeons Published by Elsevier
Conclusions. Our study demonstrates that low T3 is a strong predictor of death and low CO in CABG patients. For this reason, the thyroid profile should be evaluated before CABG, and patients with low T3 should be considered at higher risk and treated accordingly.
(Ann Thorac Surg 2014;97:2089–96) ! 2014 by The Society of Thoracic Surgeons
The T3 has a strong influence on the expression of several structural and regulatory proteins of the cardiac myocyte. Because thyroid hormone-regulated transcrip- tion is essential to maintain the physiologic cardiac phenotype, T3 deficiency has been recently proposed as a causative factor in the pathophysiology of heart failure [5, 8]. Furthermore, the low T3 syndrome has been shown to be associated with increased death in the cardiac nonsurgical patient [1, 9]. All these facts led us to hy- pothesize that the presence of a low T3 syndrome at hospital admission, as can be frequently observed in patients undergoing coronary artery bypass grafting