Initiation of hormone replacement therapy after acute myocardial infarction is associated with more cardiac events during follow-up

OBJECTIVES This study explored the association between the initiation of ho rmone replacement therapy (HRT) and early cardiac events (<1 year) in women with a recent myocardial infarction (MI). BACKGROUND Observational studies have linked postmenopausal hormone use wit h a reduced risk of death from heart disease. However, a recent randomized trial of HRT found no long-term benefit, primarily due to ail increase in c ardiac events in the first year. METHODS The Coumadin Aspirin Reinfarction Study (CARS) database contains in formation on HRT use and menopausal status for women with a recent MI. We c lassified the 1,857 postmenopausal women in CARS as prior/current HRT users if they took HRT before enrollment, new users if they began HRT during the study period or never users. We assessed the incidence of cardiac events ( death, MI, unstable angina [UA]) during follow-up. RESULS In our cohort, 28% (n = 524) used HRT at some point. Of these, 21% ( n = 111) began HRT after their MI. New users had a higher incidence of deat h/MI/UA (41% vs. 28%, p = 0.001) during follow-up than never users, largely due to a higher incidence of UA (39% vs. 20%, p = 0.001). After adjustment , new users still had a significantly higher risk of death/MI/UA than never users during follow-up (relative risk [RR] = 1.44 [1.05-1.99]). Prior/curr ent users had no excess risk of the composite end point after adjustment. U sers of estrogen/progestin had a lower incidence of death/MI/UA during foll ow-up than users of estrogen only (RR = 0.56 [0.37-0.85]). CONCLUSIONS Postmenopausal women who initiated HRT after a recent MI had an increased risk of cardiac events largely due to excess UA during follow-up . CT Am Coil Cardiol 2001;3831-7) (C) 2001 by the American College of Cardi ology.