MONDAY, Nov. 10 (HealthDay News) -- An analysis of 33 studies on drugs known as beta blockers has concluded that they are not useful in any surgical procedure other than heart surgery. In fact, using beta blockers for non-coronary surgery may actually increase the risk of stroke, the scientists say.

The researchers who conducted the study -- known as a meta-analysis -- recommend that the guidelines committees of both the American College of Cardiology and the American Heart Association "soften" their recommendations that beta blockers be used to prevent surgical complications in non-coronary operations.

"Our study says that if you look at the overall picture, do a meta-analysis, studies that are not particularly well-done come to the conclusion that they are useful," said Dr. Franz Messerli, professor of medicine at Columbia University and an author of a report published online by The Lancet to coincide with the annual heart meeting now underway. "But if you look at the high-quality studies, there are distinctly more strokes with beta blockers." Beta blockers are drugs that inhibit adrenaline and slow the nerve impulses to the heart. They can also be used to treat irregular heartbeat, known as arrhythmia.

The meta-analysis did show a 35 percent reduced risk of heart attacks and a 64 percent reduction in less serious heart artery blockages among the more than 12,000 participants in all the studies where beta blockers were prescribed before surgery. But there was no overall reduction in total deaths, heart failure or deaths due to heart disease, and a doubled risk of nonfatal stroke.

Beta blocker usage was also associated with a high risk of bradycardia, low heart rate requiring medical treatment, which occurred in 1 of every 22 people getting beta blockers, and of lower blood pressure dangerous enough to require treatment.

In September 2008, researchers writing in the Journal of the American College of Cardiology concluded that beta blocker drugs don't prevent development of heart failure in people with high blood pressure and should not be used as first-line treatment for hypertension.

The increased risk of stroke, occurring in 1 of every 293 beta blocker recipients, is especially important, Messerli said. "Stroke is one of the most devastating complications of cardiovascular disease," he said. "For that reason, we would be very reluctant to use beta blockers in noncomplicated patients."

There is a presurgical role for beta blockers in many cases, Messerli said. "If a patient has coronary artery disease, he or she should certainly be on beta blockers," he said. "If they are on beta blockers already, they should remain on beta blockers. But if there is no particular cardiovascular risk, beta blockers should not be prescribed for noncardiac procedures."

Existing recommendations that call for routine use of beta blockers before surgery should be revised, Messerli said. "This is regarded as a quality measure for physicians," he said. "If they don't prescribe a beta blocker, it is considered to be falling short of a quality measure. Since the data are relatively soft, it certainly should not be a quality measure."

But an argument for use of beta blockers before surgery was made in an accompanying comment to the study by Dr. Don Poldermans, professor of medicine at Erasmus Medical Center in Rotterdam, the Netherlands. One major problem with studies showing difficulties when beta blockers were prescribed was that the doses were too high, Poldermans said.

"A low dose is safe, so why not use it?" Poldermans said, citing a study that he presented to the American Heart Association's annual scientific sessions, in New Orleans.

The study of 1,066 people who underwent surgery and were classified as being of intermediate risk of cardiovascular complications found that 2.1 percent of those getting a moderate daily dose of bisoprolol, a widely used beta blocker, suffered heart attacks or died of heart disease, compared to 6 percent of those not getting the beta blocker, Poldermans reported.

What might help decide the issue would be "a study to clarify dose and regimen" of beta blockers before surgery, he said. But such a study might be difficult to do, because the dangers of high-dose beta blockers are clear, Poldermans said.

"I would be very careful with high doses of beta blockers," he said. "There could be an increased risk of stroke. But a low dose is safe, so why take a high dose?"

More information

Learn why and how beta blockers are used from the Texas Heart Institute.