Background: Although postmenopausal hormone therapy (HRT) commonly is used in hope of preventing coronary heart disease, the effect of HRT on case fatality of myocardial infarction has never been studied. We evaluated HRT as a predictor of survival after MI in postmenopausal women.
Methods and results: The present study was performed with 114 724 women of age >/=55 years with confirmed myocardial infarction who presented between April 1998 and January 2000 to 1 of 1674 hospitals participating in the National Registry of Myocardial Infarction-3. Presenting characteristics, treatment, and clinical outcome data were obtained by chart review. At time of hospitalization, 7353 (6.4%) women reported current use of HRT, defined as use of estrogen, progestin, or estrogen/progestin for reasons other than contraception. Unadjusted mortality was 7.4% in users of HRT and 16.2% in nonusers (odds ratio 0.41, 95% confidence interval 0.36 to 0.43). After adjustments were made for prior medical history, clinical characteristics, treatments received in-hospital, and likelihood of receiving HRT, HRT remained associated with an improved rate of survival (odds ratio 0.65, 95% confidence interval 0.59 to 0.72). Significant association of HRT with decreased mortality after myocardial infarction was observed in all age strata.
Conclusions: Postmenopausal HRT appears to be associated with reduced mortality after myocardial infarction. This finding could be caused by therapeutic effect of HRT, selection and adherence bias, or some combination of both.