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Trial Reveals an Increased Risk of Mortality and Stroke Among Patients Given Beta Blockers After Noncardiac Surgery

NEW YORK -- May 12, 2008 -- The results of the Perioperative Ischemic Evaluation (POISE) trial, published in an early online and upcoming edition of The Lancet, have shown that patients given beta blockers after noncardiac surgery have a higher risk of death or stroke than those given placebo.

P. J. Devereaux, MD, McMaster University, Hamilton, Ontario, and colleagues from the POISE study group conducted a randomised controlled trial to investigate the effects of perioperative beta blockers. The study was performed in 190 hospitals across 23 countries. 8,351 patients with, or at risk of atherosclerotic disease who were undergoing noncardiac surgery, defined as all surgeries other than heart surgery, were randomised to receive the beta blocker, metoprolol succinate (n = 4,174), or placebo (n = 4,177). Treatment was started 2 to 4 hours prior to surgery and continued for 30 days. The primary endpoints were cardiovascular death, nonfatal heart attack, or nonfatal cardiac arrest.

The researchers found that fewer patients in the metoprolol group reached the primary endpoint (n = 244) than in the placebo group (n = 290), making those in the metoprolol group 16% less likely to reach this endpoint. Fewer patients in the metoprolol group (n = 176) than the placebo group (n = 239) had a heart attack, a reduction in risk of 27% for the metoprolol group. However, there were more deaths in the metoprolol group (n = 129) than in the placebo group (n = 97), representing a 33% increased risk for the metoprolol group. In addition, more patients had a stroke in the metoprolol group (n = 41) than the placebo group (n = 19) -- more than double the risk.

According to the authors, "Results suggest that for every 1,000 patients with a similar risk profile undergoing noncardiac surgery, extended-release metoprolol would prevent 15 patients from having a heart attack, 3 from undergoing cardiac revascularization [including coronary artery bypass graft (CABG) surgery or angioplasty], and 7 from developing new and significant atrial fibrillation. The results also suggest that extended-release metoprolol would result in an excess of 8 deaths, 5 patients having a stroke, 53 experiencing clinically significant hypotension, and 42 experiencing clinically significant bradycardia for every 1,000 treated."

The authors concluded that, "for every 15 patients who participated in POISE, 1 had a cardiovascular death, nonfatal heart attack, nonfatal cardiac arrest, or nonfatal stroke at 30-day follow-up. In view of the large numbers of individuals undergoing surgery and the high risk of cardiovascular complications, more large trials are needed urgently. ... Our results highlight the risk in assuming a perioperative beta-blocker regimen has benefit without substantial harm. Patients are unlikely to accept the risk associated with perioperative extended-release metoprolol."

In an accompanying comment, Lee A. Fleisher, MD, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, and Don Poldermans, MD, Erasmus Medical Centre, Rotterdam, Netherlands, agreed that the POISE study clearly shows that acute administration of higher-dose beta-blocker therapy in the perioperative period is associated with greater risk than benefit. But they also discussed the differing implications the study could have on daily clinical practice, depending on the indication for beta blockers in the individual patient.

They also discussed that other protocols using a low-dose beta-blocker regimen have established a beneficial effect on postoperative outcome without an increased incidence of stroke. They recommended the use of beta blockers carefully in the perioperative period, in a low dose, to be supervised by clinicians who are experienced in haemodynamic care during surgery.

SOURCE: The Lancet

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