Administration of tibolone decreases 24 h heart rate but not blood pressure of post-menopausal women

Abstract

Objective: Elevation of blood pressure and heart rate increase the risk of cardiovascular disease. Administration of estrogens does not affect heart rate but may decrease 24 h blood pressure. In this study, we tested the effect of the estro-progestogenic compound tibolone. Methods: Thirty healthy, post-menopausal women were randomized to receive placebo ( n=15) or tibolone, at the commonly prescribed dose of 2.5 mg per day ( n=15). Before and after 6 months of treatment, in each woman blood pressure and heart rate were monitored every 30 min for 41 h by an ambulatory device. Valuable readings were those collected from 8:00 a.m. of the second day to 8:00 a.m. of third day. Analyses were performed of 24 h, day-time (7:00 a.m.–11:00 p.m.) and night-time (11:00 p.m.–7:00 a.m.) values. Day to night difference was also calculated. Results: Placebo did not modify 24 h, day-time, and night-time blood pressure or heart rate values. Day–night differences were also not affected by placebo. Similarly to placebo, tibolone administration did not modify any of the blood pressure parameters taken into consideration. By contrast, a significant decline of 24 h heart rate (73.2±2.3 beats/min versus 69.3±1.7 beats/min; P<0.0008) was observed. The effect was significant both at day (76.6±2.4 beats/min versus 72.1±1.9 beats/min; P<0.0001) and night (65.8±2.6 beats/min versus 62.4±1.9 beats/min; P<0.05). Day–night blood pressure and heart rate differences were not affected by tibolone. Conclusions: In post-menopausal women, administration of tibolone does not influence 24 h blood pressure but reduces heart rate.