Researchers in Canada have found that almost three-quarters of acute cardiac events in premenopausal women occur between days one and five of the menstrual cycle. The study, which was reported at the annual meeting of the American College of Clinical Pharmacy, raises the possibility that fluctuations in oestrogen levels could be involved in precipitating heart attacks in women at risk of heart disease.
Bettina Hamelin from the Hôpital Lavel, in conjunction with colleagues at the Quebec Heart Institute, studied 28 premenopausal women who had been admitted to hospital with unstable angina or acute myocardial infarction. According to Dr Hamelin, all subjects had at least one risk factor for heart disease: specifically, 43% had hypercholesterolemia, 42% were hypertensive and 36% were current smokers. In addition, 24% were former smokers and 7% were diabetic.
Significantly, 71% of the cohort suffered the acute coronary event within five days after onset of menstruation. Twenty women had their coronary event three days or less after beginning menses and eight women had it after seven days from the start of menstruation.
The investigators believe that fluctuations in circulating levels of 17β-oestradiol during the menstrual cycle may modulate the risk of coronary events. Low oestrogen levels are already known to be associated with an increased risk of heart disease in postmenopausal women. "Our study shows that in premenopausal women who have risk factors for heart disease, the time of menses may make them particularly vulnerable to an acute attack," Hamelin notes. In an ACCP statement the group call for larger trials to confirm these preliminary findings, but stress that in the meantime "young women need to be counselled about their risk factors for heart disease, and older women should continue to be counselled about the benefits of oestrogen replacement therapy."