A common medication given to patients to prevent heart complications during and after surgery may in fact increase the risk of stroke and even death, a new Canadian study says.
The research showed that beta blockers, which help reduce the effects of stress hormones on the heart during and after surgery, reduced the risk of heart attack but increased the risk of stroke and death.
Out of the 4,174 patients who received the beta blocker metoprolol succinate prior to and for 30 days after surgery, only 176 suffered a heart attack, compared to 239 among the 4,177 patients who received a placebo.
However, patients who received the beta blocker were 33 per cent more likely to die than patients in the placebo group. As well, patients on metoprolol were twice as likely than placebo patients to suffer a stroke.
The study, entitled POISE, was published in the online edition of the journal The Lancet. It included more than 8,000 patients from 23 countries who had undergone any operation other than heart surgery.
Dr. P.J. Devereaux, lead study author and a cardiologist and epidemiologist at McMaster University in Hamilton, Ont., told CTV.ca that beta blockers are a common treatment during and after surgery to lower both heart rate and blood pressure to reduce the risk of heart complications.
However, many patients undergoing surgery usually fall into a state of shock, characterized by low blood pressure. Therefore, the beta blockers may prevent blood-pressure levels from rising back to levels needed to sustain life.
According to McMaster, more than 100 million people undergo non-cardiac surgery every year, with about one million suffering some sort of heart complication, such as heart attack or even death. For over a decade, general surgical guidelines have indicated that surgeons should give their patients beta blockers before and after surgery.
This could mean that thousands of surgical patients in the last decade have been adversely affected by taking beta blockers.
"Let's just say that 10 per cent of physicians acted on the guidelines. What that would mean is that in the last decade, 100 million adults would have been given peri-operative beta-blockers," said Devereaux.
"If the POISE results are widely applicable, which we believe they are, that would mean that in the last decade, because of these guidelines, 800,000 people would have died prematurely and half a million people would have suffered a major stroke around the time of surgery because they were given the beta blockers."
Devereaux said that the findings suggest that doctors must re-evaluate the wisdom of using beta blockers. He said that doctors could decide not to use them altogether while other drugs to reduce heart complications are studied.
Abstract:
E铿�ects of extended-release metoprolol succinate in patients undergoing non-cardiac surgery (POISE trial): a randomised controlled trial
Background: Trials of 锟� blockers in patients undergoing non-cardiac surgery have reported con铿俰cting results. This randomised controlled trial, done in 190 hospitals in 23 countries, was designed to investigate the e铿�ects of perioperative 锟� blockers.
Methods: We randomly assigned 8351 patients with, or at risk of, atherosclerotic disease who were undergoing non-cardiac surgery to receive extended-release metoprolol succinate (n=4174) or placebo (n=4177), by a computerised randomisation phone service. Study treatment was started 2-4 h before surgery and continued for 30 days. Patients, health-care providers, data collectors, and outcome adjudicators were masked to treatment allocation. The primary endpoint was a composite of cardiovascular death, non-fatal myocardial infarction, and non-fatal cardiac arrest. Analyses were by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00182039.
Findings: All 8351 patients were included in analyses; 8331 (99锟�8%) patients completed the 30-day follow-up. Fewer patients in the metoprolol group than in the placebo group reached the primary endpoint (244 [5锟�8%] patients in the metoprolol group vs 290 [6锟�9%] in the placebo group; hazard ratio 0锟�84, 95% CI 0锟�70-0锟�99; p=0锟�0399). Fewer patients in the metoprolol group than in the placebo group had a myocardial infarction (176 [4锟�2%] vs 239 [5锟�7%] patients; 0锟�73, 0锟�60-0锟�89; p=0锟�0017). However, there were more deaths in the metoprolol group than in the placebo group (129 [3锟�1%] vs 97 [2锟�3%] patients; 1锟�33, 1锟�03-1锟�74; p=0锟�0317). More patients in the metoprolol group than in the placebo group had a stroke (41 [1锟�0%] vs 19 [0锟�5%] patients; 2锟�17, 1锟�26-3锟�74; p=0锟�0053).
Interpretation: Our results highlight the risk in assuming a perioperative 锟�-blocker regimen has bene铿乼 without substantial harm, and the importance and need for large randomised trials in the perioperative setting. Patients are unlikely to accept the risks associated with perioperative extended-release metoprolol.
