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Background: Hormone replacement therapy (HRT) is associated with reduced cardiovascular risk, but the underlying mechanism(s) are not fully understood. This study investigated the effects of a 6-month course of HRT on cardiac autonomic function parameters assessed by heart rate variability (HRV) in postmenopausal women.Methods: Forty-six healthy postmenopausal women (age 48 +/- 5, range 40-60) with normal baseline electrocardiogram and negative exercise testing were enrolled. HRT, which was either 0.625 mg/day conjugated equine estrogen (CEE) plus 2.5 mg/day medroxyprogesterone acetate or 0.625 mg/day CEE alone were administered depending on hysterectomy status. Power spectral analysis of HRV was performed to calculate the low frequency component in absolute (LF) and normalized units (LF nu), high frequency component in absolute (HF), and normalized units (HF nu), and the LF/HF ratio. The standard deviation of RR intervals (SDNN) was calculated from the time series of RR intervals.Results: A 6-month course of HRT did not significantly alter resting heart rate (P > 0.05). The LF/HF ratio and LF nu significantly decreased after HRT (P = 0.022 and P = 0.032), whereas a significant increase was noted in the HF component of HRV (P = 0.043), indicating an improvement in cardiac autonomic function. The SDNN value, which was 28.8 +/- 11.8 ms before HRT significantly increased to 35.4 +/- 16.7 ms after 6 months (P = 0.011).Conclusion: Our results indicate that a 6-month course of HRT may significantly improve cardiac autonomic function parameters, a finding that could at least partly explain the potential cardioprotective effect(s) of HRT. [ABSTRACT FROM AUTHOR]

Background: The aim of the study was to investigate the effects of hormone replacement therapy (HRT) on myocardial repolarization characteristics in postmenopausal women without coronary artery disease.Methods: Fifty-one consecutive healthy postmenopausal women (age 48 +/- 5) with negative exercise stress testing were prospectively enrolled into the study. Standard 12-lead electrocardiograms were obtained to evaluate the effects of 6 months of HRT on QT intervals, corrected QT intervals (QTcmax and QTcmin), QT dispersion (QTd), and corrected QTd (QTcd). Hormone regimens were continuous 0.625 mg/day conjugated equine estrogen (CEE) plus 2.5 mg/day medroxyprogesterone acetate (MPA) or 0.625 mg/day CEE alone depending on the hysterectomy status.Results: Although not statistically significant, CEE alone or in combination with MPA increased QTmax and QTmin values. However, the increase in QTmin was greater than the increase in QTmax, which resulted in statistically significant shortening of QTd (P = 0.007 in CEE and P < 0.001 in CEE + MPA groups). There was a significant prolongation of QTcmin values after 6 months in patients assigned to the CEE group (P = 0.001). The QTcd values were significantly shortened by HRT with both regimens (for CEE group 49 +/- 13 ms vs 38 +/- 13 ms, P = 0.01; for CEE + MPA group 49 +/- 14 ms vs 36 +/- 13, P < 0.001).Conclusion: HRT significantly decreased the QTd and QTcd in postmenopausal women without coronary artery disease, independent of the addition of MPA to the regimen. This improvement in myocardial repolarization may be one of the mechanisms of the favorable effects of HRT on cardiovascular system. However, the clinical implications of the shortening of QTd in postmenopausal women with HRT must be clarified. [ABSTRACT FROM AUTHOR]

Objective: Autoimmune chronic thyroiditis (ACT) is characterized by lymphocyte infiltration in the thyroid gland and the presence of antithyroid antibodies in serum. Medical treatment does not affect antibody levels and treatment decision is not definite yet for the euthyroid patients. We aimed to evaluate cardiac autonomic function and global left ventricular performance in autoimmune euthyroid chronic thyroiditis and determine the need for medical treatment., Method: We studied 30 ACT patients and 25 healthy control subjects. Cardiac autonomic function is evaluated by heart rate recovery (HRR). Global left ventricular performance is evaluated by two-dimensional echocardiography and pulsed-wave tissue Doppler echocardiography., Results: There was no difference between patients and controls with respect to clinical and biochemical parameters except hemoglobin (13.67 ± 1.25 g/dL, 14.51 ± 1.35 g/dL, p:0.047) and low density lipoprotein (120.71 ± 24.91 mg/dL, 100.55 ± 14.73 mg/dL, p: 0.003). Tei index was significantly higher in ACT group (0.521 ± 0.074, 0.434 ± 0.034, P < 0.0001). E'/A' was found to be significantly lower (1.234 ± 0.42, 1.750 ± 0.291, P < 0.0001) and E/E' was found to be higher than the controls (8.482 ± 0.449, 6.039 ± 0.209, P < 0.0001). HRR was significantly lower than the controls (20 ± 4 BPM, 30 ± 8 BPM, P < 0.0001)., Conclusion: Although left ventricular performance is found to be normal by conventional echocardiographic methods, it is found to be impaired when Tei index and tissue Doppler parameters are used. Cardiac autonomic function is also impaired in ACT patients. As a result of these cardiac changes, medical treatment may be considered earlier, even at the euthyroid stage., (© 2010, Wiley Periodicals, Inc.)

Objective: To evaluate the effects of treatment on left ventricular (LV) performance and endothelial function in patients with acromegaly., Method: Nineteen patients with active acromegaly (AA), 18 patients with cured/well-controlled acromegaly (CA), and 25 healthy control subjects were studied. LV performance was evaluated by two-dimensional/Doppler echocardiography and Doppler tissue imaging (TDI). Flow-mediated dilatation (FMD) was measured by B-mode ultrasound. Endothelial cell markers; thrombomodulin (TM), and P-selectin were also measured., Results: Tei index was higher than the control subjects in both acromegaly groups. The ratio of early and late diastolic annular velocities (Em'/Am') was significantly lower in the AA group than the other groups (P < 0.05). FMD in both acromegaly groups was significantly lower than the controls (P < 0.001) but difference between acromegaly groups was not significant (P > 0.05). In the CA group, P-selectin was higher than the controls and was even higher in the AA (P < 0.05). TM was significantly higher in the active group (P < 0.05) and not different than the controls in the CA group., Conclusion: TDI determine LV performance changes in acromegaly earlier than conventional echocardiographic methods. Endothelial function both in the form of FMD and endothelial cell markers is impaired in acromegaly. While in cured acromegaly endothelial cell injury, as evidenced by TM levels, is decreased, endothelial dysfunction still persists., (© 2010, the Authors Journal compilation © 2010, Wiley Periodicals, Inc.)