Beta blockers show mixed results in patients undergoing noncardiac surgery

ORLANDO, Nov. 7 – Beta blockers, a class of anti-ischemic drugs, might help protect patients who are at risk for atherosclerotic cardiovascular disease from suffering post-operative cardiovascular events, such as heart attacks, when they undergo noncardiac surgery, according to research reported at a late-breaking clinical trial presentation at the American Heart Association’s Scientific Sessions 2007.

The Perioperative Ischemic Evaluation (POISE) trial is the largest, randomized controlled trial to access whether risks of post-operative cardiovascular events can be lowered by beta blockers.

The study enrolled 8351 patients to determine the impact of the beta blocker metoprolol on the 30-day risk of major cardiovascular events in people who are undergoing noncardiac surgery.   These patients were at risk of atherosclerotic cardiovascular disease.   Researchers used a large pool to detect plausible and relevant relative risk reductions, researchers said.

Patients received an oral dose of 100 mg controlled-release (CR) metoprolol or placebo two to four hours before surgery and between zero and six hours after surgery.   Twelve hours following the first post operative dose, patients started taking daily doses of metoprolol or placebo at 200 mg and continued for 30 days after surgery.   If at any time patients could not take doses orally, 15 mg of the drug or normal saline as a placebo was administered intravenously every six hours until patients were ready to switch back to oral doses.

Patients qualified to participate if they were undergoing noncardiac surgery, were 45 or older, had an expected hospital stay greater than 24 hours, and had experienced either coronary heart disease, peripheral arterial disease, stroke, congestive heart failure within three years of randomization, or major vascular surgery.

“Our study found strong evidence that perioperative CR metoprolol prevents heart attacks but there is also concerning evidence that it increases the risk of death and stroke,” said P.J. Devereaux, M.D., principal investigator of the trial and assistant professor in the department of clinical epidemiology and biostatistics at McMaster University in Hamilton, Ontario, Canada.  “Findings also demonstrated that with metoprolol there was a decrease in atrial fibrillation and in the need for coronary revascularization an increase in clinically significant hypotension and bradycardia.”

Devereaux said clinicians considering perioperative B-blocker therapy should seek input from patients on their perspective on the trade-off between potential benefits and harms.

Support for this study was provided by AstraZeneca.

Statements and conclusions of study authors that are presented at American Heart Association scientific meetings are solely those of the study authors and do not necessarily reflect association policy or position.  The American Heart Association makes no representation or warranty as to their accuracy or reliability.

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