Acute administration of conjugated equine oestrogen does not improve exercise-induced myocardial ischaemia in men with coronary artery disease

Background: The parenteral administration of oestradiol acutely protects against exercise-induced myocardial ischaemia in women, but whether this effect is sex -specific is not known. Aims: The effects of acutely administered conjugated equine oestrogen on exercise-induced myocardial ischaemia in men with established coronary heart disease were investigated in a randomized, placebo--controlled, double-blind cross-over trial. Methods: Twenty men, aged 62 +/- 11.6 years, with reproducible exercise-induced myocardial ischaemia were treated with either intravenous conjugated equine oestrogen (25 mg) or saline prior to undergoing an exercise stress test. Primary end-points were total exercise time and time to 1 mm ST-segment depression. Results: All participants completed the protocol. Total exercise time exceeded the baseline value in 17 of the 20 men following saline, and in 17 of the 20 men following oestrogen pretreatment. Time to 1 mm ST-segment depression exceeded the baseline value in 14 of the 19 men following saline, and following oestrogen administration, exceeded baseline in 13 of the 19 men. There was no significant difference between the two treatments in either time to 1 mm ST-segment depression or total exercise time. A period effect was apparent for total exercise time (P = 0.05) but not for time to ST-segment depression. Conclusions: Acute parenteral oestrogen therapy did not increase total exercise time or time to the onset of electrocardiographic changes of ischaemia in men with chronic stable coronary artery disease. These findings contrast the favourable effects of oestrogen in women in comparable studies and indicate a sex specificity for the acute cardiovascular effects of oestrogen.