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Aspirin Clonidine Do Not Protect Against Death or Heart Attack in Non-Cardiac Surgeries

POISE-2 Trial Spanned 135 Centers in 23 Countries

Monday, March 31, 2014

Two medications commonly used during non-cardiac surgery – aspirin and clonidine – do not protect against heart attacks or death any better than placebo, according to data presented as a late-breaking clinical trial at the American College of Cardiology’s 63rd Annual Scientific Session and published simultaneously by the New England Journal of Medicine.

Daniel I. Sessler, M.D., professor and chairman of Outcomes Research at Cleveland Clinic, presented the clonidine data from the POISE-2 trial (PeriOperative ISchemic Evaluation-2), the largest study of clonidine in surgical patients. P.J. Devereaux, MD, PhD, associate professor of epidemiology and cardiology at McMaster University, presented the POISE-2 aspirin data.

More than 10,000 patients from135 centers in 23 countries were randomized to receive clonidine (a beta blocker that reduces blood pressure and heart rate) or placebo (0.2 mg/day) just prior to surgery, which was continued until 72 hours after surgery. Simultaneously, they were randomized to receive aspirin (100 mg/day) just before surgery, which was continued for seven to 30 days.

Incidence of heart attack and/or death within 30 days of the surgery – the trial’s primary outcome – did not differ significantly between those treated with clonidine (325 patients, 6.5 percent) and those given placebo (293 patients, 5.9 percent).

Patients treated with clonidine were more likely to experience nonfatal cardiac arrest and clinically significant hypotension (low blood pressure) – without any improvement in mortality.

Hypotension, as expected, was more common in patients assigned to clonidine (2,386 patients, 47.6 percent) than placebo (1,854 patients, 37.1 percent). And nonfatal cardiac arrest was more common among patients using clonidine (16 patients, 0.3 percent) than those on placebo (5 patients, 0.1 percent.) However, mortality rates in the two groups were identical (1.3 percent).

The POISE-2 findings on aspirin were similar. The rate of deaths and nonfatal heart attacks (7 percent) were identical in patients taking aspirin and those on placebo. However, major bleeding was more common in the aspirin group (236 patients, 4.7 percent) versus the placebo group (188 patients, 3.8 percent).

“POISE-2 demonstrates that clonidine does not reduce death or heart attacks in non-cardiac surgery. If anything, it worsens the outcome, probably by reducing blood pressure,” Dr. Sessler said. “Aspirin also fails to prevent heart attacks after surgery.

“Still, a substantial problem persists – 7 percent of adults died or suffered a nonfatal myocardial infarction in the first 30 days after surgery. Considering that low-dose clonidine is not a means to minimize these complications, new strategies are needed to tackle the problem of major vascular complications after non-cardiac surgery.”

The study was funded by the Canadian Institutes of Health Research and none of the investigators has a personal financial interest in the research.

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