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Prospective association between hormone replacement therapy, heart rate, and heart rate variability. The
Mercedes R Carnethon1, Mary S Anthony, Wayne E Cascio
1Stanford Center for Research in Disease Prevention, Stanford University School of Medicine, 1000 Welch Road, Palo Alto, CA 94304, USA. carnethon@northwestern.edu
Insights
Postmenopausal hormone replacement therapy did not show associations with heart rate (HR) or heart rate variability (HRV) in this observational study. Further research via randomized trials is recommended to confirm these findings on hormone therapy and cardiovascular health.
Area of Science:
- Cardiovascular Health
- Endocrinology
- Autonomic Nervous System Function
Background:
- Observational studies frequently link hormone replacement therapy (HRT) to coronary heart disease (CHD).
- The potential role of the autonomic nervous system (ANS) in mediating this association remains unclear.
- Understanding HR and HRV changes associated with HRT is crucial for assessing cardiovascular risk.
Purpose of the Study:
- To investigate the association between postmenopausal hormone replacement therapy and autonomic nervous system function.
- To test the hypothesis that HRT use is linked to more favorable heart rate (HR) and heart rate variability (HRV) measures.
- To examine the influence of HRT on cardiovascular markers in a population-based sample of women.
Main Methods:
- An observational study involving a population sample of 2,621 women.
- Hormone therapy use was assessed across four examinations starting in 1987.
- Supine heart rate and heart rate variability indices were measured over 6 minutes during 1996-1998.
Main Results:
- Unadjusted analyses indicated that hormone therapy users had lower HR and higher HRV compared to non-users.
- After adjusting for age and established CHD risk factors, these associations between HRT and HR/HRV were no longer statistically significant.
- The findings suggest no direct link between hormone therapy and autonomic nervous system markers in this cohort.
Conclusions:
- This observational study suggests that hormone replacement therapy is not associated with heart rate or heart rate variability.
- The previously observed associations may be confounded by other cardiovascular risk factors.
- Randomized controlled trials are necessary to definitively establish the relationship between HRT and cardiovascular autonomic function.
Abstract:
Hormone replacement therapy is universally associated with coronary heart disease (CHD) in observational studies, but it is unknown whether this association is mediated by the autonomic nervous system. We tested the hypothesis that postmenopausal hormone replacement therapy was associated with more favorable heart rate (HR) and heart rate variability (HRV) in a population sample of women (n=2,621). Hormone therapy use was measured at four examinations beginning in 1987. Supine HR and HRV indices were measured for 6 minutes at the final examination (1996-1998). In unadjusted linear regression models, hormone therapy was associated with lower HR (hormone use=64.7 vs. never=65.7 beats/min, P=.01) and higher HRV. However, following adjustment for age and CHD risk factors, both associations were eliminated. Results from this observational study suggest that hormone therapy is not associated with HR or HRV. These analyses should be replicated in a randomized trial.