Conference Coverage
Neither perioperative aspirin nor clonidine prevents MI
Major finding: The primary outcome of death or MI occurred in 7% of the aspirin group and 7.1% of the placebo group, a nonsignificant difference;...
ANAHEIM, CALIF. – For every 1,000 patients with a history of percutaneous coronary intervention undergoing noncardiac surgery, perioperative aspirin would prevent 59 myocardial infarctions but cause 8 major/life-threatening bleeds, according to a substudy of the POISE-2 trial presented at the American Heart Association scientific sessions.
For patients with previous PCI undergoing noncardiac surgery, “I think aspirin will be more likely to benefit them than harm them,” so long as they are not having an operation where bleeding would be devastating.” These include “delicate neurosurgery in which, if you bleed into your spine, you end up paralyzed,” said lead investigator Michelle Graham, MD, an interventional cardiologist and professor of cardiology at the University of Alberta, Edmonton.
Dr. Michelle Graham
The original multisite POISE-2 trial (Perioperative Ischemic Evaluation 2) evaluated the effect of perioperative aspirin for noncardiac surgery. Patients were randomized to receive 200 mg aspirin or placebo within 4 hours of surgery and then 100 mg aspirin or placebo in the early postoperative period. There was no significant effect on the composite rate of death or myocardial infarction, but an increased risk of serious bleeding (N Engl J Med. 2014 Apr 17;370[16]:1494-503).
The new substudy focused on the 470 patients with previous PCIs, because such patients are known to have a higher risk for postop complications. More than half received bare-metal stents and a quarter got drug-eluting stents; in most of the rest, the stent type was not known. The median duration from PCI to noncardiac surgery was 64 months, ranging from 34 to 113 months. Patients with bare-metal stents placed within 6 weeks or drug-eluting stents within a year, were excluded.
Overall, 234 patients were randomized to the aspirin group, and 236 to placebo. Among those who came in on chronic, daily aspirin therapy – as almost all of the PCI subjects did – those who were randomized to perioperative aspirin stayed on daily 100 mg aspirin for a week postop, and then flipped back to whatever dose they were on at home. Likewise, placebo patients resumed their home aspirin after 1 week.
The results were very different from the main trial. At 30 days’ follow-up, just 6% of patients in the aspirin arm reached the primary endpoint of death or MI, versus 11.5% in the placebo group, a statistically significant 50% reduction.
This difference was driven almost entirely by a reduction in MIs. Whereas 5.1% of patients in the aspirin arm had MIs, 11% of the placebo group did, a significant 64% reduction. Meanwhile, the risk of major or life-threatening bleeding was not only similar between groups, but also to the overall trial, noted in 5.6% of aspirin and 4.2% of placebo subjects.
Over 75% of the participants were men, almost 60% were undergoing a major surgery, 30% had diabetes, and many had hypertension. Very few were on direct oral anticoagulants. The two arms were well matched, with a median age of about 68 years.
Simultaneously with Dr. Graham’s presentation, the results were published online (Ann Intern Med. 2017 Nov 14; doi: 10.7326/M17-2341)
The work was funded mostly by the Canadian Institutes of Health Research. Bayer supplied the aspirin. Dr. Graham has no industry disclosures.