engleski

Cardiovascular Effects of Thyroxine in Combination with Methimazole in Premenopausal Female Graves' Disease Patients

AIM. To evaluate cardiovascular consequences of combined treatment in patients with Graves' disease with addition of thyroxine (LT4) to antithyroid drugs in doses sufficient to suppress serum thyrotropin (TSH) levels below normal. METHODS. Eleven premenopausal female patients who reached subnormal TSH levels (<0.3 &#956; IU/mL) under the combined therapy were evaluated by equilibrium radionuclide ventriculography at rest and during peak stage of fixed moderate exercise workload (75W) initially at diagnosis and after at least 8 months of stable euthyroidism, as judged by peripheral free thyroxine and triiodothyronine. Control group included 12 euthyroid healthy women. RESULTS. Post-treatment resting systolic (SBP) and diastolic blood pressure (DBP), heart rate and left ventricular (LV) systolic function were similar to control values. Log-transformed TSH releasing factor-stimulated TSH response correlated with LV resting early diastolic peak filling rate (PFR) (r=0.802, p=0.003) and resting DBP (r=0.795, p=0.003), which, in turn, was a significant predictor of basal renin secretion (r=-0.84, p=0.001). Treated patients had increased peak exercise (Ex) SBP in comparison with controls (181&plusmn ; ; 28.8 vs 158&plusmn ; ; 16.7 mmHg, p=0.019), delayed recovery of post-exercise HR to basal levels and reduced exercise ejection fraction (EF) (67&plusmn ; ; 5.3 vs 73&plusmn ; ; 3.1%, p=0.037). ExEF was inversely related to ExDBP, (r=-0.818, p=0.002) ; and ExSBP to exercise time to PFR in a heart rate-independent manner, r partial=0.89, p<0.001). CONCLUSION. Persistent TSH suppression in LT4-treated Graves' disease patients promotes pressure dependent renin secretion, modulates resting early LV diastolic relaxation and is associated with exaggerated ExSBP response and decreased EF response to exercise.

hyperthyroidism; renin; systolic function; exercise; ventriculography; blood pressure

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