An invasive treatment approach appears to reduce risk for rehospitalization, myocardial infarction or death for men and high-risk women with unstable angina or non-ST-segment elevation myocardial infarction, but it may increase risk for infarction or death in low-risk women, according to an article in the July 2 issue of Journal of the American Medical Association.

Previous authors had concluded that although an invasive strategy is frequently used in patients with unstable angina and non-ST-segment elevation myocardial infarction, the approach may not benefit women, with a possible higher risk of death or infarction, according to background information in the article. "Thus, the benefit of an invasive strategy in women remains unclear. However, individual trials have not been large enough to explore outcomes reliably within subgroups," the authors wrote.

For the current meta-analysis, an invasive strategy was defined as referral of all patients with myocardial infarctions and unstable angina for cardiac catheterization prior to hospital discharge. A conservative treatment strategy was defined as a primary strategy of medical management and subsequent catheterization only for patients with ongoing chest pain or a positive stress test.

Michelle O'Donoghue, MD, of Brigham and Women's Hospital and Massachusetts General Hospital, Boston, and colleagues analyzed eight randomized trials to examine the benefits and risks of an invasive strategy in women versus in men with unstable heart disease. Data were combined, and the incidence of death, myocardial infarction, or rehospitalization with unstable angina or myocardial infarction was analyzed for 10,150 patients, 3,075 women and 7,075 men.

Women who received invasive treatment had a 19 percent lower risk for the composite of death, infarction, or acute coronary syndrome compared with women who received conservative treatment (21.1 percent versus 25.0 percent); men had a 27 percent lower risk for the composite compared with men who received conservative treatment (21.2 percent versus 26.3 percent).

Among high-risk biomarker-positive women, invasive treatment was associated with a 33 percent lower risk of the composite outcome and a nonsignificant 23 percent lower risk of death or infarction.

In contrast, an invasive strategy was not associated with a significant reduction in the triple composite end point in biomarker-negative women and was associated with a nonsignificant 35 percent higher risk of death or infarction. Among men, the risk for the composite outcome was 44 percent lower if biomarker-positive and 28 percent lower if biomarker-negative.

"Our data provide evidence to support the updated American College of Cardiology/American Heart Association guidelines that now recommend that a conservative strategy be used in low-risk women with non-ST-segment elevation acute coronary syndromes [NSTE ACS]," the authors wrote.

"Combination of these data enabled us to explore the association of sex with outcomes both overall and within high-risk subgroups, whereas individual studies may be insufficiently powered in this regard. Future investigations should include novel methods for identifying women at high-risk of adverse outcomes after NSTE ACS and whose risk could be modifiable with an invasive approach."