title: Echocardiographic characterization of the reversible cardiomyopathy of hypothyroidism.
abstract: Nineteen patients with untreated hypothyroidism were evaluated by M-mode echocardiography. Asymmetric septal hypertrophy (ASH), defined as a ratio of interventricular septal thickness to left ventricular posterior wall thickness (IVS/LVPW) equal to or greater than 1.3, was identified in 17 cases. Additional abnormalities recognized by echocardiography included reduced amplitude of systolic septal excursion (SSex) [13 patients], reduced per cent of systolic septal thickening (%SST)[19 patients], reduced left ventricular outflow tract dimension (LVOT)[five patients] and systolic anterior motion of the mitral valve (SAM)[five patients]. These findings are similar to some of the echocardiographic features of idiopathic hypertrophic subaortic stenosis (IHSS). In 10 patients who returned to euthyroid state with L-thyroxine therapy, these abnormalities resolved. We conclude that long-standing hypothyroidism leads to a reversible cardiomyopathy, manifested by asymmetric septal hypertrophy with or without other echocardiographic features of a hypertrophic obstructive cardiomyopathy. This previously unrecognized features of hypothyroidism has important diagnostic and therapeutic implications.
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002302:Cardiac Output; D006332:Cardiomegaly / Q000209:etiology / Q000473:pathology; D002312:Cardiomyopathy, Hypertrophic / Q000209:etiology* / Q000473:pathology; D004452:Echocardiography; D005260:Female; D006346:Heart Septum / Q000473:pathology; D006801:Humans; D007037:Hypothyroidism / Q000150:complications* / Q000188:drug therapy; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000473:pathology; D013974:Thyroxine / Q000627:therapeutic use
chemical_list: D013974:Thyroxine