A research team surprised itself with findings that hormone replacement therapy can actually be harmful in women who have established coronary heart disease (CHD).
The US Heart and Estrogen/progestin Replacement Study (HERS); found that HRT caused early harm and late benefits in these women. The clinical trial documented more coronary events in the study group than in the placebo group, plus an increased rate of thromboembolisms and gallbladder disease.
HERS recommended that HRT should not be prescribed for secondary prevention of CHD, but that it should be continued in women already taking it (The Lancet, 1998; 352: 627). These findings differ markedly from most observational data (JAMA, 1998; 280: 650-651).