Patients who receive clonidine during noncardiac surgery may have an increased risk of hypotension and nonfatal cardiac arrest, according to research presented March 31 at the American College of Cardiology (ACC) scientific session in Washington, D.C.

The Perioperative Ischemic Evaluation 2 (POISE-2) trial evaluated whether perioperative administration of a low dose of clonidine (Catapress, Boehringer Ingelheim) compared to placebo lowered the 30-day risk of death or nonfatal MI in patients at risk for atherosclerotic disease.

POISE-2 investigators, led by P.J. Devereaux, MD, PhD, of the Population Health Research Institute at McMaster University in Hamilton, Ontario, Canada, compared low-dose clonidine to placebo and low-dose aspirin to placebo in more than 10,000 patients in 23 countries with or at risk for atherosclerosis who underwent noncardiac surgery.

Participants in the clonidine comparison arm received either 0.2 mg of clonidine per day or placebo right before surgery and continued the drug until three days after surgery. Patients in the aspirin arm received aspirin or placebo right before surgery and continued to receive aspirin during the postoperative period. The primary outcome was a composite of death or nonfatal MI at 30 days.

Compared with placebo, clonidine did not reduce occurrence of the primary outcome (339 events in the placebo group and 367 in the clonidine group, hazard ratio [HR] for clonidine, 1.08). The rate of MI was 6.6 percent in the clonidine group and 5.9 percent in the placebo group.

Clinically important hypotension was significantly more common in the clonidine group (47.6 percent) compared with the placebo group (37.1 percent). Clonidine was also associated with an increased rate of nonfatal cardiac arrest (0.3 percent vs 0.1 percent for placebo).

Based on their findings, the researchers argued that “[n]ew strategies are needed to address the problem of major vascular complications after noncardiac surgery.”

The results were published simultaneously in The New England Journal of Medicine.

In a separate paper, the investigators noted that aspirin did not significantly affect the rate of the composite of death or nonfatal MI, but did significantly increase the risk of major bleeding.

Boehringer Ingelheim provided the clonidine and some funding for the research.