Effects of thyroid hormone on left ventricular function in patients treated for thyrotoxicosis

• Published in: The American journal of cardiology Vol. 48; no. 1; pp. 33 - 38
• Main Authors: Cohen, Michael V., Schulman, Ira C., Spenillo, Angelo, Surks, Martin I.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-07-1981
• Subjects: Adult; Electrocardiography; Female; Heart Rate - drug effects; Heart Ventricles - drug effects; Humans; Hyperthyroidism - drug therapy; Male; Middle Aged; Propranolol - therapeutic use; Systole - drug effects; Thyroid Hormones - therapeutic use; Thyroxine - blood; Triiodothyronine - blood
• ISSN: 0002-9149; 1879-1913
• DOI: 10.1016/0002-9149(81)90569-5

Systolic time intervals, echocardiographic indexes of left ventricular contractile function and serum triiodothyronine and thyroxine levels were measured before treatment in nine patients with hyperthyroidism, and again every 2 weeks for the first 2 months after therapy and then every 4 weeks until the subjects were clinically and chemically euthyrold. Six of the nine became transiently hypothyroid. Although the preejection period corrected for heart rate (preejection period index) increased as the patients became euthyroid, the change was not significant. Preejection period Index increased dramatically in the patients becoming hypothyroid (
p <0.005). Corrected left ventricular ejection time (left ventricular ejection time index) also increased as the patients became euthyroid (
p <0.001), and Increased again with the appearance of hypothyroidism (
p <0.05). There was a linear correlation between velocity of circumferential fiber shortening and serum triiodothyronine level (
r = 0.77) and between velocity of circumferential fiber shortening and serum thyroxine level (
r = 0.70) at all stages of thyroid function. Thus thyroid hormone definitely enhances left ventricular function in human beings, and both excess and deficiency cause predictable reversible changes in myocardial contractile function. Furthermore echocardiographic measurements of velocity of circumferential fiber shortening provide rapid estimates of the chemical status of thyrotoxic patients before and after treatment.