Related Hot Line Update: OASIS 5: Worse outcome with an invasive strategy among women with non ST-elevation acute coronary syndromes
Professor Eva Swahn, from the University Hospital in Linköping, Sweden, descibed a small randomised trial in women with NSTE ACS. The OASIS 5 women sub-study compared early routine coronary angiography (and, if appropriate, coronary revascularisation within seven days) with a wait-and-see approach in which coronary angiography was performed only when women had signs or symptoms of angina.
The study included 184 patients and was too small to provide conclusive evidence. However, the trends were worrying, said Swahn. There was no significant difference in rates of myocardial infarction (MI), worsening of angina, or stroke. But at one year, eight patients in the early invasive group had died (all cardiovascular deaths), compared with one patient (from bleeding) in the wait-and-see group. The difference persisted at two years.
This finding adds yet more confusion to determining the best strategy for women with NTSE ACS. The first suggestion of a problem with a routine invasive approach in women came from the FRISCII study in 2001, which was then backed by findings from RITA3 in 2002.
However, these results were contradicted by TACTICS, also in 2002, which found higher rates of MI deaths in the wait-and-see group.
“With such alarming results in our very small trial,” she said, “we need to conduct a large randomised trial to determine the safety and efficacy of an early invasive approach in women.”
This may be easier said than done. The current study was intended to include 1600 women, but far fewer were actually recruited. All but three subjects were in Sweden and Poland; six countries in the larger OASIS study did not recruit for the women sub-study at all.
Swahn said that many doctors were reluctant to include women specifically in the sub-study because they would receive different treatment from the standard approach in men. But she said: “Only large studies will show for certain that we are treating women in the best way for women, and men in the best way for men.”
Possible explanations for the gender difference include higher rates of bleeding among women, and differences in the optimal doses of medication. But, said Swahn, “we do not have the answer to these questions.”