Menopausal Hormone Therapy and Risks of First Hospitalized Heart Failure and its Subtypes During the Intervention and Extended Postintervention Follow-up of the Women's Health Initiative Randomized Trials

Background: We assessed whether postmenopausal hormone therapy (HT) was associated with incident heart failure (HF) and its subtypes and examined whether there was a modifying effect of age on the associations. Methods and Results: Postmenopausal women aged 50-79 enrolled in the Women's Health Initiative HT trials were analyzed. The 16,486 women with a uterus were randomized to receive conjugated equine estrogens (CEE 0.625 mg/day) plus medroxyprogesterone acetate (MPA 2.5 mg/day) or placebo, and 10,739 women with prior hysterectomy were randomized to receive CEE (0.625 mg/day) alone or placebo. Incident HF was defined as the first HF hospitalization. HF with reduced ejection fraction (HFrEF) or preserved EF (HFpEF) was defined as EF < 50% or >= 50%. During the intervention phase, median follow-up was 5.6 years in the CEE-plus-MPA trial and 7.2 years in the CEE-alone trial. During the cumulative follow-up of 18.9 years, women randomized to HT vs placebo in the 2 combined trials had incidence rates of 3.90 vs 3.89 per 1000 person-years for total HF; 1.25 vs 1.40 per 1000 person-years for HFrEF, and 1.88 vs 1.79 per 1000 person-years for HFpEF, respectively. There were no significant effects of HT on the risk of total incident HF or its subtypes in either trial, and age at randomization did not significantly modify the results. Conclusions: Postmenopausal HT did not alter the risk of hospitalization for HF or its subtypes during the intervention or cumulative 18.9 years of follow-up, and results did not vary significantly by age at randomization.