Effect of Short-Term L-Thyroxine Therapy on Left Ventricular Mechanics in Idiopathic Dilated Cardiomyopathy

Previous experimental studies have provided evidence of notable changes in thyroid hormone signaling that corresponds to alterations in myocardial function in animal models of heart failure (HF). The present study further explores whether oral thyroid hormone treatment can change left ventricular (LV) mechanics and functional status in patients with idiopathic dilated cardiomyopathy (IDCM) or not. Sixty IDCM patients who were receiving conventional HF treatment were randomized to oral L-thyroxine (n = 40) or placebo (n = 20) for 3 months. Fifty-two (86.7%) of all IDCM patients were symptomatic, their mean age was 41 ± 12 years, and their ejection fraction was 32% ± 7%. At baseline, the two groups were comparable in clinical and echocardiographic variables. Vector velocity imaging was utilized to assess LV mechanics. Myocardial longitudinal peak systolic strain, systolic strain rate, early and late diastolic strain rate, circumferential strain, LV dyssynchrony, plasma tri-iodothyronine, thyroxine, and thyroid stimulating hormone levels were measured at baseline and 3 months after treatment. All patients receiving L-thyroxine significantly improved in functional status (New York Heart Association class; P