A secondary analysis of the Women's Health Initiative trials examined cardiovascular risks of menopausal hormone therapy in 27,347 women with vasomotor symptoms, stratified by age group. In women aged 50–59, both estrogen alone and estrogen-plus-progestin therapy reduced hot flashes significantly without meaningfully increasing atherosclerotic cardiovascular disease risk. Women aged 60–69 showed a mixed picture with no definitive harm signal. However, women aged 70–79 with vasomotor symptoms who took hormone therapy faced dramatically elevated cardiovascular risk — nearly double with estrogen alone and more than triple with combined therapy. These findings offer the strongest randomized evidence yet that age is the decisive factor in whether hormone therapy is safe for the heart.
