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Starting Hormone Therapy After MI Increases Risk for Cardiac Events
Despite the reduction in cardiovascular risk seen in observational studies of postmenopausal women on hormone therapy (HT), recent randomized trials of HT have shown no reduction in this risk. The Heart and Estrogen/progestin Replacement Study also found an unexpected increase in myocardial infarctions (MIs) within the first year of combination HT treatment.
To examine whether HT initiation is associated with subsequent risk for cardiovascular disease in women with pre-existing coronary artery disease, these authors conducted a partially manufacturer-supported study of 1857 postmenopausal women who were enrolled in the Coumadin Aspirin Reinfarction Study after an MI. A total of 111 women who first started HT after their MIs (new users) were compared with 413 past or current users and 1333 never-users. HT use was not randomized.
Compared with never-users, past/current users and new users were younger and were more likely to smoke and have a college education. Oral estrogen alone was the most common form of HT, used by 67 percent of past/current users and 69 percent of new users; combination therapy (oral estrogen and progesterone) was used by 28 percent and 27 percent, respectively.
Over 8 to 23 months of follow-up, new users were significantly more likely to have unstable angina than were never-users (39 percent vs. 20 percent). Among new users, those taking estrogen alone were at greater risk for both unstable angina and cardiac events overall than those on combination therapy. Compared with never-users, past/current users did not have a significant increase in risk for cardiac events with continued use, and they had a lower risk for death (they were also younger than never-users). No deaths occurred among the new users.
Comment: This study did not include randomized assignment of HT; however, the investigators were able to analyze subsequent cardiovascular events in a unique group of women who initiated HT only after their first heart attack. These findings support recently issued statements advising that the initiation of HT may be detrimental to women with known coronary artery disease. The mechanisms behind the increase in risk are unclear but likely involve the effect of HT on thrombosis and atherosclerotic plaque stability.
Alternatives to HT for postmenopausal women with coronary artery disease include bisphosphonates, exercise, and calcium to address bone-mineral density issues; vaginal rings or tablets (which have little systemic absorption) to treat genital atrophy and vaginal dryness; and antidepressants (e.g., venlafaxine or paroxetine) for vasomotor symptoms.
— MC Limacher
Published in Journal Watch Women's Health September 18, 2001
Citation(s):
Alexander KP et al. Initiation of hormone replacement therapy after acute myocardial infarction is associated with more cardiac events during follow-up. J Am Coll Cardiol 2001 Jul 38 1-7.
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