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Sex steroids and heart rate variability in patients after myocardial infarction
Jerzy Krzysztof Wranicz1, Marcin Rosiak, Iwona Cygankiewicz
1Department of Cardiology, Medical University of Lodz, Lodz, Poland. holter@csk.am.lodz.pl
Insights
Higher testosterone levels in men after myocardial infarction are linked to better heart rate variability, indicating improved autonomic nervous system function. This suggests testosterone may positively impact cardiac autonomic regulation.
Area of Science:
- Cardiology
- Endocrinology
- Autonomic Nervous System Research
Background:
- Controversies exist regarding sex steroids' role in coronary artery disease (CAD).
- Autonomic nervous system dysfunction is observed in CAD patients, particularly post-myocardial infarction.
- The relationship between sex steroids and circadian autonomic activity in CAD patients remains understudied.
Purpose of the Study:
- To investigate the association between sex steroid levels and heart rate variability (HRV) parameters in men following a myocardial infarction.
- To explore the influence of testosterone and estradiol on autonomic cardiac regulation in postinfarction patients.
Main Methods:
- 88 men (average age 53) post-myocardial infarction underwent 24-hour Holter monitoring to assess HRV.
- Hormone levels, including testosterone and estradiol, were measured.
- Univariate and multivariate regression analyses were employed to examine relationships between HRV and hormone levels.
Main Results:
- Increased testosterone levels correlated with higher HRV parameters: SDNN, rMSSD, and pNN50.
- These associations remained significant after adjusting for clinical covariates.
- No significant association was found between estradiol levels and HRV parameters.
Conclusions:
- Higher testosterone levels are associated with enhanced parasympathetic activity, as indicated by HRV measures, in men post-myocardial infarction.
- Testosterone may exert a beneficial effect on the heart's autonomic regulation.
- Estradiol did not show a significant association with HRV in this cohort.
Background:
Although the relationship between sex steroid levels and coronary artery disease (CAD) has been the subject of many studies there are still controversies concerning the role of sex steroids in CAD. In patients with CAD, especially after a myocardial infarction, there is evidence for autonomic nervous system dysfunction. However, there is no data detailing the relationship between sex steroids and cicardian autonomic activity in patients with CAD. The aim of the study was to evaluate the association between sex steroids and heart rate variability (HRV) parameters in postinfarction patients.
Methods:
In 88 postinfarction men (aged 36-73, average 53 years), 24-hour Holter monitoring was performed to assess HRV parameters: SDNN, SDNNI, SDANN, rMSSD, pNN50, and levels of the following hormones were measured: testosterone, estradiol, free testosterone index, and estradiol/testosterone ratio. Univariate and multivariate regression analyses were used to investigate the relationship between HRV parameters and levels of tested hormones.
Results:
Increased testosterone levels were associated with increased SDNN (r = 0.38, P = 0.03), increased rMSSD (r = 0.51, P = 0.002), and increased pNN50 (r = 0.45, P = 0.007). These associations remained significance after adjustment for age, ejection fraction, and other relevant clinical covariates. There was no significant association between estradiol and HRV parameters.
Conclusion:
In men with a history of myocardial infarction, higher levels of testosterone are associated with higher HRV measures of parasympathetic activity. These findings suggest that testosterone beneficially influences autonomic regulation of the heart.
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