Middle-aged women without heart disease had significantly lower baroreflex sensitivity compared to men (8.0 vs 10.5 ms/mm Hg; P<0.001), but augmented tonic vagal modulation of heart rate.
Cross-Sectional (n=374)
Are there sex-related differences in the autonomic modulation of heart rate in middle-aged subjects without known heart disease?
Middle-aged women exhibit attenuated baroreflex responsiveness but augmented tonic vagal modulation of heart rate compared to men, with estrogen replacement therapy appearing to have favorable autonomic effects.
Absolute Event Rate: 8% vs 10.5%
p-value: p=<.001
BACKGROUND: Women have worse outcomes when they experience acute myocardial infarction (MI), but the reasons for this sex-related difference are not well understood. Because cardiovascular neural regulation plays an important role in cardiac mortality, we studied possible sex-related differences in the autonomic modulation of heart rate (HR) in middle-aged subjects without known heart disease. METHODS AND RESULTS: Baroreflex sensitivity (BRS) and HR variability were studied in randomly selected, age-matched populations of middle-aged women (n = 186; mean age, 50 +/- 6 years) and men (n = 188; mean age, 50 +/- 6 years) without hypertension, diabetes, or clinical or echocardiographic evidence of heart disease. BRS measured from the overshoot phase of the Valsalva maneuver was significantly lower in women (8.0 +/- 4.6 ms/mm Hg, n = 152) than in men (10.5 +/- 4.6 ms/mm Hg, n = 151) (P < .001), and the low-frequency component of HR variability measured from ECG recordings also was lower in women (P < .001), whereas the high-frequency component was higher in women than in men (P < .001). The ratio between the low-and high-frequency oscillations also was lower in the women (P < .001). The increase of HR and decrease of high-frequency component of HR variability in response to an upright posture were smaller in magnitude in women than in men (P < .01 for both). After adjustment for differences in the baseline-variables, such as blood pressure, HR, smoking, alcohol consumption, and psychosocial score, the sex-related differences in BRS and HR variability still remained significant (P < .001 for all). Women with estrogen replacement therapy (n = 46) had significantly higher BRS and total HR variance than the age-matched women without hormone treatment (P < .01 for both), and the BRS and HR variability of the women with estrogen therapy did not differ from those of the age-matched men. CONCLUSIONS: Baroreflex responsiveness is attenuated in middle-aged women compared with men, but the tonic vagal modulation of HR is augmented. Hormone replacement therapy appears to have favorable effects on the cardiovascular autonomic regulation in postmenopausal women.
Huikuri et al. (Mon,)는 건강한 중년 피험자(n=374)를 대상으로 단면 연구를 수행하였고, 여성 성별과 남성 성별에 대한 바론 반사 민감도(BRS)를 평가하였다(p=<.001). 심장 질환이 없는 중년 여성은 남성에 비해 바론 반사 민감도가 유의미하게 낮았다(8.0 vs 10.5 ms/mm Hg; P<0.001) 하지만 심박수의 강화된 톤 신경절 제어가 있었다.