Using beta-blocker drugs like metopropolol during surgery might help prevent heart attacks, but they could increase the risk of death and major stroke, a new study has found

The findings are based on POISE, the world's largest randomised trial addressing perioperative cardiac complications.

The trial evaluated the effects of a beta-blocker versus placebo given to patients around the time of surgery.

"POISE demonstrates that a beta-blocker given around the time of surgery decreases a patient's risk of a heart attack but increases their risk of a major stroke and death," The Lancet quoted Dr. P.J. Devereaux, POISE co-principle investigator, McMaster University, Hamilton, Canada, as saying.

Surgery boosts patients' catecholamines, or stress hormones, which increase the heart's requirement for oxygen.

And stress on the heart can cause serious events such as a heart attack.

Since beta-blockers reduce the effects of increased catecholamines some doctors thought that they might prevent serious heart complications around the time of surgery.

"Initial small trials suggested beta-blockers were beneficial around the time of surgery but more recent moderate sized trials did not show any benefit. We undertook POISE to provide a clearer understanding of the effects of a beta-blocker around the time of surgery," Dr. Homer Yang, POISE co-principal investigator, University of Ottawa, Ottawa, Canada.

Dr. Salim Yusuf, POISE steering committee chair, McMaster University, Hamilton, Canada, said: "A major accomplishment of POISE was that anesthesiologists, cardiologists, internists, and surgeons at 190 centres in 23 countries came together and randomised 8,351 patients - more than 4 times as many patients than all the previous perioperative beta-blocker trials combined. Such efforts are rare, but essential in order to make progress in the management of these patients."