Background: The risk of coronary heart disease is much lower in the premenopausal women compared to age matched men. The present study assessed the effect of cyclical alteration in female sex hormones on cardiac autonomic activity by HRV. Materials & Methods: The present study was conducted on 56 eumenorrheic women volunteers with regular menstrual cycle aging between 20-30 years with normal BMI. Last menstrual period (LMP) and menstrual history were collected. After 10 minutes rest ECG analysis was done. Recordings were done in the morning during proliferative phase (6th -7 th day) and premenstrual phase (24th - 25th day). Results: Low frequency (LF) in proliferative phase was 84.12 and in premenstrual phase was 87.35, high frequency (HF) was 15.6 in proliferative phase and in premenstrual phase was 12.3, LF/HF ratio was 5.4 and 6.8 in proliferative phase and premenstrual phase respectively. The difference was significant (P< 0.05). Total power found to be 4487 ms2and 3452 in proliferative phase and premenstrual phase respectively. The difference was significant (P< 0.05). Conclusion: Cardioprotective role of female sex hormones in premenopausal women was more pronounced in the proliferative phase of menstrual cycle.
Key words: Cardiac autonomic, Premenopausal, Sex hormones.