OBJECTIVE: Previous studies have suggested that hypothyroidism affects both systolic and diastolic cardiac function. We have applied equilibrium radionuclide angiography to the study of heart function at rest in hypothyroidism. DESIGN: A prospective study, evaluating cardiac function at rest in primary hypothyroidism. METHODS: Cardiac function was studied by means of equilibrium radionuclide angiography. Screening echo-Doppler examinations were performed on each patient. PATIENTS: Twenty-six consecutive untreated hypothyroid patients without clinical or echocardiographic cardiac disease and 20 healthy matched controls. RESULTS: Between patients and controls, the time to peak emptying rate (161 ± 6 msec vs. 144 ± 6 msec, P < 0.05) and the time to peak filling rate (188 ± 6 msec vs. 170 ± 5 msec, P < 0.05), were the only discriminatory parameters. In hypothyroid patients, a trend towards a decrease in diastolic cardiac function, expressed as peak filling rate, was observed: 2.6 ± 0.1 End Diastolic Volume (EDV)/s vs. 3.0 ± 0.1 EDV/s, P = 0.06. Within the hypothyroid patient group, the time to peak emptying rate was more prolonged in patients with lower free thyroxine levels (R = -0.60, F = 13.5, P < 0.001). Peak filling rate was decreased in patients with lower free thyroxine levels (R = 0.51, F = 8.4, P < 0.01) whereas the time to peak filling rate was more prolonged (R = -0.62, F = 15, P < 0.001). CONCLUSION: In a large group of consecutive patients presenting with primary hypothyroidism, even in the absence of clinical cardiac disease and echocardiographic abnormalities, clear changes in myocardial performance at rest were observed. The most obvious effect of thyroid hormone deficiency on the heart was a lengthening of both systolic and early diastolic time characteristics. Diastolic rather than systolic cardiac function was influenced by hypothyroidism.

Additional Metadata
Persistent URL dx.doi.org/10.1046/j.1365-2265.1999.00662.x, hdl.handle.net/1765/54274
Journal Clinical Endocrinology
Tielens, A.G.M, Pillay, M, Storm, C, & Berghout, A. (1999). Cardiac function at rest in hypothyroidism evaluated by equilibrium radionuclide angiography. Clinical Endocrinology, 50(4), 497–502. doi:10.1046/j.1365-2265.1999.00662.x