Yildirir A, Kabakci G, Yarali H, Aybar F, Akgul E, Bukulmez O, Tokgozoglu L, Gurgan T, Oto A
Department of Cardiology, Hacettepe University, Ankara, Turkey.
Ann Noninvasive Electrocardiol. 2001 Oct;6(4):280-4. doi: 10.1111/j.1542-474x.2001.tb00119.x.
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.
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.
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).
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.
激素替代疗法（HRT）与心血管风险降低相关，但其潜在机制尚未完全明确。本研究调查了为期6个月的HRT疗程对绝经后女性通过心率变异性（HRV）评估的心脏自主神经功能参数的影响。
纳入46名健康绝经后女性（年龄48±5岁，范围40 - 60岁），其基线心电图正常且运动试验阴性。根据子宫切除状态给予HRT，即每日0.625mg结合马雌激素（CEE）加每日2.5mg醋酸甲羟孕酮，或仅每日0.625mg CEE。进行HRV的功率谱分析以计算绝对低频成分（LF）和标准化单位（LF nu）、绝对高频成分（HF）和标准化单位（HF nu）以及LF/HF比值。从RR间期的时间序列计算RR间期的标准差（SDNN）。
为期6个月的HRT疗程未显著改变静息心率（P>0.05）。HRT后LF/HF比值和LF nu显著降低（P = 0.022和P = 0.032），而HRV的HF成分显著增加（P = 0.043），表明心脏自主神经功能有所改善。HRT前SDNN值为28.8±11.8ms，6个月后显著增加至35.4±16.7ms（P = 0.011）。
我们的结果表明，为期6个月的HRT疗程可能显著改善心脏自主神经功能参数，这一发现至少可以部分解释HRT的潜在心脏保护作用。
