Thyroid Hormones—An Underestimated Player in Dilated Cardiomyopathy?

Abstract

Dilated cardiomyopathy (DCM) is the most prevalent cardiomyopathy, typified by left ventricular dilation and systolic dysfunction. Many patients with DCM have altered thyroid status, especially lower levels of free triiodothyronine (T3) and elevated levels of thyroid-stimulating hormone. Moreover, growing evidence indicates that even subtle changes in thyroid status (especially low T3) are linked with a worse long-term prognosis and a higher risk of mortality. Notably, recent discoveries have shown that not only local myocardial thyroid hormones (THs) bioavailability could be diminished due to impaired expression of the activating deiodinase, but virtually all genes involved in TH biosynthesis are also expressed in the myocardium of DCM patients. Importantly, some studies have suggested beneficial effects of TH therapy in patients suffering from DCM. Our aim was to discuss new insights into the association between TH status and prognosis in DCM, abnormal expression of genes involved in the myocardial synthesis of TH in DCM, and the potential for TH use in the future treatment of DCM.

Generalized pitting edema in a patient with dilated cardiomyopathy secondary to hypothyroidism

“…Thyroid hormones are known to mediate genomic and nongenomic effects on the heart, and recent studies have shown changes in gene expression associated with biosynthesis or diminished bioavailability of thyroid hormones at the tissue level among patients with dilated cardiomyopathy. 7 Cardiac dysfunction among patients with dilated cardiomypathy secondary to hypothyroidism can be reversed with thyroid hormone replacement therapy. 3,6 Although hypothyroidism alone is an uncommon cause of dilated cardiomyopathy, clinicians should perform thyroid function tests in patients with un explained dilated cardiomyopathy.…”

Subclinical hypothyroidism and dilated cardiomyopathy (DCM) in children

“…Karolina Zawadzka published a review in 2021, Radosław Dziedzic [4] showed that not only the local bioavailability of myocardial thyroid hormones could be decreased due to altered expression of desiodase, but practically all genes involved in thyroid hormone biosynthesis are expressed in the myocardium.…”

Œdème à godet généralisé chez un patient présentant une myocardiopathie dilatée secondaire à une hypothyroïdie

“…Le mécanisme exact d'apparition de la myocardiopathie dilatée chez la patientèle atteinte d'hypothyroïdie reste à déterminer. Outre l'action connue des hormones thyroïdiennes sur le coeur, passant par des effets génomiques et non génomiques, des études récentes ont permis de constater des variations de l'expression génique associées à la biosynthèse ou à la diminution de la biodisponibilité de ces hormones dans les tissus de la patientèle atteinte de myocardiopathie dilatée 7 . La dysfonction cardiaque de la patientèle atteinte de myocardiopathie dilatée secondaire à une hypothyroïdie peut être réversible avec une hormonothérapie thyroïdienne substitutive 3,6 .…”