Postmenopausal hormone therapy and major adverse cardiac events in women with prior myocardial infarction

Abstract Background Hormone therapy for postmenopausal symptoms is contraindicated in women with a prior cardiovascular event but is still used. Further investigation is needed regarding the risk of a subsequent cardiovascular event in these women. Purpose To investigate the rate of reinfarction, stroke, or cardiovascular death in women using hormone therapy following a myocardial infarction compared to those who did not. Methods All Danish women ≥ 50 years of age with a first-time acute myocardial infarction diagnosis during the study period from January 2000 to December 2021 were identified using the Danish nationwide registers. Time zero was defined as 90 days after their myocardial infarction, and women were followed for up to three years or until the occurrence of a major adverse cardiac event (MACE), all-cause mortality, emigration, or December 31, 2022. Hormone therapy use was defined as at least one prescription redemption of a hormone therapy drug in the 90 days following their myocardial infarction diagnosis. A Cox proportional hazards model, adjusted for age at infarction, calendar year of infarction, income level, diabetes, cancer, peripheral vascular disease, hypertension, kidney disease, heart failure, atrial fibrillation, and chronic obstructive pulmonary disease, was used to estimate the hazard ratio for MACE. MACE was defined as a composite outcome of reinfarction, stroke or cardiovascular death. Results Among 43,932 women who experienced acute myocardial infarction and survived at least 90 days the mean age at time zero was 76.8 (± 9.6) and 4,488 (10.2%) had redeemed a hormone therapy drug prescription. In total, 13,169 (30.0%) experienced MACE within 3 years. Among women using hormone therapy 1,125 (25.1%) experienced MACE while it was 12,044 (30.5%) of those who did not. Hormone therapy was not significantly associated with MACE within 3 years (hazard ratio: 0.95 (95% CI: 0.89-1.01)). Conclusion Hormone therapy use following acute myocardial infarction was not associated with increased or decreased rate of reinfarction, stroke or cardiovascular death. Knowledge about the benefits and possible harms of hormone therapy is important in decision making when treating women for postmenopausal symptoms and should be further investigated.