Evaluation of diastolic function in newly diagnosed hyperthyroid patients with preserved left ventricular systolic function.

Background: Diastolic dysfunction has been reported as a cardiovascular effect of hyperthyroidism, and is also supposed to be a cause of heart failure manifestations in the patients with preserved ejection fraction (EF).

Methods: For evaluation of diastolic function in hyperthyroid patients and also diastolic function during performing exercise stress echocardiography, we conducted this study on 25 newly diagnosed hyperthyroid patients compared to 26 healthy subjects as control group. Diastolic function of the patients at rest was assessed using these parameters as follows: left atrium volume index, tricuspid regurgitation (TR) velocity, mitral inflow early diastolic flow (E wave), tissue Doppler of mitral annular velocity (e'), E/e' ratio, and isovolumic relaxation time (IVRT); and during exercise stress echocardiography, we judged diastolic response by measuring E/e' ratio and TR velocity at the peak of stress.

Results: The mean age of the patients was 39.64 ± 12.23 years old and 52% of them were female. History of exertional dyspnea was found in 64% of patients. All the patients had normal diastolic function at the time of resting and there was no significant difference in diastolic parameters between the two groups except for IVRT, which was lower in hyperthyroid patients. Interestingly, no patients developed diastolic dysfunction during exercise stress echocardiography.

Conclusion: Our finding did not show diastolic dysfunction in hyperthyroid patients neither at rest nor during exercise echocardiography and did not support the hypothesis that diastolic dysfunction can be a cause of exertional intolerance and dyspnea in the patients with preserved EF.