methimazole and Hypertrophy--Left-Ventricular

Cardiac structure and function are affected both by acromegaly and hyperthyroidism. Whereas the former is mainly characterized by ventricular hypertrophy as well as diastolic and systolic impairment, the latter frequently leads to increased heart rate and enhancement of contractility and cardiac output. To further investigate this issue, we designed this two-arm study. In the first cross-sectional study, we compared echocardiography and radionuclide angiography results obtained in eight hyperthyroid acromegalic patients, eight hyperthyroid nonacromegalic patients, and eight healthy subjects. All acromegalic patients were receiving treatment for acromegaly at the onset of hyperthyroidism. In the second longitudinal study, performed in the group of acromegalic patients, we compared the cardiovascular results obtained during hyperthyroidism with the retrospective data obtained at the initial diagnosis of acromegaly and after 1-yr treatment for this disease and those prospective data obtained during the remission of hyperthyroidism. In the cross-sectional study, hyperthyroid acromegalic patients showed an increase in the left ventricular (LV) mass index (LVMi) compared to healthy and hyperthyroid controls (P < 0.05), with evidence of LVMi hypertrophy in five of them (62.5%). A significant correlation was found between LVMi and GH levels (r = 0.785; P < 0.05). The LV ejection fraction (LVEF) at rest was higher in the control hyperthyroid population than in healthy controls (P < 0.05), whereas the LVEF response to exercise was reduced in acromegalic patients (P < 0.05 vs. healthy controls). In acromegalics, the exercise-induced change in LVEF was significantly reduced compared to that in healthy controls (P < 0.001), but not to that in hyperthyroid controls (P < 0.07), being abnormal (<5% increase vs. baseline values) in six patients. Four of these six patients (66%) had elevated GH and insulin-like growth factor I levels during the treatment of acromegaly. An inverse correlation between GH and LVEF at rest (r = -0.896;P < 0.05) and at peak exercise (r = -0.950; P < 0.001) was recorded. The peak filling rate was reduced in hyperthyroid acromegalic patients compared to those in both control populations (P < 0.05). In the longitudinal study, acromegalic patients showed an increased LVMi during hyperthyroidism compared to that observed after successful treatment of acromegaly (P < 0.05); resting LVEF was increased compared to both basal (P < 0.001) and posttreatme

Topics: Acromegaly; Antithyroid Agents; Echocardiography; Female; Heart Diseases; Human Growth Hormone; Humans; Hypertrophy, Left Ventricular; Insulin-Like Growth Factor I; Iodine Radioisotopes; Longitudinal Studies; Male; Methimazole; Middle Aged; Radionuclide Angiography; Thyrotoxicosis; Ventricular Function, Left