Women who have coronary artery disease should not be started on hormone replacement therapy because it may increase the risk of thromboembolic complications, such as stroke, say cardiologists from Papworth hospital.
Dr Sarah Clarke from the hospital's cardiac unit announced this finding during a presentation of the Papworth HRT Atherosclerosis Study (PHASE) at the 22nd annual congress of the European Society of Cardiology on August 29.
The PHASE study showed that HRT patches did not reduce the risk of angina requiring admission to hospital, heart attacks or death from heart disease, and gave no extra reduction in blood cholesterol in women with confirmed coronary artery disease.
In the four-year study, 255 women with confirmed coronary artery disease were randomised either to receive or not to receive treatment with HRT patches.
It was found that admission to hospital for angina was increased in women receiving HRT, mostly during the first two years of treatment.
Overall, although there was no significant difference in the number of cardiac events between the groups, angina requiring admission to hospital, heart attacks or death from heart disease were slightly more common in the group who were using HRT patches. There was also a trend towards an increase in thromboembolic complications, such as stroke, in the HRT group, said Dr Clarke.
"It may be that certain women have a greater risk of thromboembolic complications and such women need to be identified and not prescribed HRT," said Dr Clarke. However, it "may be appropriate" for those women who had been taking HRT for more than two years to continue, she added. This was because the small increase in the risk of suffering cardiac complications was noted only during the first two years of treatment with HRT.
The PHASE results are supported by the findings of the US heart and estrogen/progestin replacement study (HERS), which found that, compared with a placebo group, slightly more heart attacks occurred in the first year of treatment with HRT in women with established heart disease.
Another US study, the Estrogen Replacement and Atherosclerosis (ERA) trial, also found no cardiovascular benefit from using HRT in women with cardiovascular disease (PJ, April 15, p573). The ERA study was published recently in the New England Journal of Medicine (2000;343:522).
Commenting on the results of the ERA study, Dr David Herrington, the lead researcher for the trial, said: "A possible explanation for HRT's lack of effect on disease progression is that oestrogen may also cause an adverse inflammatory response in the arteries that offsets the beneficial cholesterol effects. Or perhaps HRT is better at preventing heart disease in younger, healthier women than at reversing disease in older women."