A very interesting paper that re-confirms what so many here have said - hypothyroidism affects the heart. But with a concerning point that correcting that hypothyroidism rapidly actually damages the heart. Anyway, thankfully, you can follow the link to read the full paper. Though that doesn't say what the the optimum approach might be. And it is all from rats.
PLoS One. 2014 Oct 15;9(10):e109753. doi: 10.1371/journal.pone.0109753. eCollection 2014.
Hypothyroidism and its rapid correction alter cardiac remodeling.
Hajje G1, Saliba Y1, Itani T2, Moubarak M1, Aftimos G2, Farès N1.
The cardiovascular effects of mild and overt thyroid disease include a vast array of pathological changes. As well, thyroid replacement therapy has been suggested for preserving cardiac function. However, the influence of thyroid hormones on cardiac remodeling has not been thoroughly investigated at the molecular and cellular levels. The purpose of this paper is to study the effect of hypothyroidism and thyroid replacement therapy on cardiac alterations. Thirty Wistar rats were divided into 2 groups: a control (n = 10) group and a group treated with 6-propyl-2-thiouracil (PTU) (n = 20) to induce hypothyroidism. Ten of the 20 rats in the PTU group were then treated with L-thyroxine to quickly re-establish euthyroidism. The serum levels of inflammatory markers, such as C-reactive protein (CRP), tumor necrosis factor alpha (TNF-α), interleukin 6 (IL6) and pro-fibrotic transforming growth factor beta 1 (TGF-β1), were significantly increased in hypothyroid rats; elevations in cardiac stress markers, brain natriuretic peptide (BNP) and cardiac troponin T (cTnT) were also noted. The expressions of cardiac remodeling genes were induced in hypothyroid rats in parallel with the development of fibrosis, and a decline in cardiac function with chamber dilation was measured by echocardiography. Rapidly reversing the hypothyroidism and restoring the euthyroid state improved cardiac function with a decrease in the levels of cardiac remodeling markers. However, this change further increased the levels of inflammatory and fibrotic markers in the plasma and heart and led to myocardial cellular infiltration. In conclusion, we showed that hypothyroidism is related to cardiac function decline, fibrosis and inflammation; most importantly, the rapid correction of hypothyroidism led to cardiac injuries. Our results might offer new insights for the management of hypothyroidism-induced heart disease.
PMID: 25333636 [PubMed - in process]