Compared with conservative management, invasive treatment of unstable angina with non-ST-segment elevation myocardial infarction does not benefit women who show no elevation of biomarkers of necrosis, according to a meta-analysis of eight clinical trials.
Moreover, invasive therapy potentially increases the risk of death or subsequent MI in this group of low-risk women with NSTEMI, reported Dr. Michelle O'Donoghue of Brigham and Women's Hospital, Boston, and her associates.
In contrast, invasive therapy does benefit women who have unstable angina with NSTEMI who show elevated biomarkers of necrosis, and their benefit is comparable with that of men with NSTEMI, the meta-analysis shows.
These findings support the recently updated American College of Cardiology/American Heart Association guidelines “that now recommend a conservative strategy be used in low-risk women with NSTE ACS [non-ST-elevation acute coronary syndromes],” Dr. O'Donoghue and her associates said.
The investigators undertook a meta-analysis of the issue because “individual trials have not been large enough to explore outcomes reliably within subgroups,” and previous analyses have yielded disparate results. The meta-analysis included 10,412 patients randomly assigned to receive conservative or invasive treatment for NSTE ACS.
“Among women with an elevated cardiac biomarker, an invasive strategy significantly decreased the odds of death, MI, or rehospitalization with ACS by 33%, which was comparable with the benefit observed overall in men,” the researchers said (JAMA 2008;300:71-80).
“In contrast, women without biomarker elevation did not appear to have a significant benefit from an invasive strategy and had a nonsignificant higher odds of death or MI compared with those treated conservatively,” they noted.
For both men and women, those randomly assigned to an invasive strategy had a higher rate of death or MI before hospital discharge than did those randomly assigned to conservative management, but after discharge, showed a significant reduction in death or MI rates.
“We also observed that women are significantly less likely than men to have obstructive CAD [coronary artery disease] at the time of angiography, despite a clinical presentation consistent with NSTE ACS. Overall, 24% of women randomized to an invasive strategy had no evidence of significant epicardial CAD at angiography, vs. only 8% of men” Dr. O'Donoghue and her associates added.
These results “emphasize the need for larger prospective trials to specifically examine the benefit of an invasive strategy in women,” they noted.