Beta blockers are a type of drug used to lower blood pressure and prevent abnormal heart rhythms. These properties may well account for the drugs' benefit for patients at risk for cardiac problems with surgery, the researchers said.
Patients in the study had undergone one of several types of non-heart surgery: general, vascular, orthopedic, neurosurgery, chest, ear/nose/throat and urologic.
"Beta blockers appear to reduce the risk of dying or having a heart attack or cardiac arrest 30 days after surgery," said lead researcher Dr. Martin London, of the U.S. Department of Veterans Affairs Medical Center and University of California, San Francisco.
The possible protective effect of beta blockers for people having non-heart surgery has been a topic of controversy for close to 30 years, London said, with a lot of conflicting information and confusion.
In the new observational study, London's team found that patients who had two or more risk factors for heart problems had the most benefit from beta blockers -- including lower 30-day mortality -- when undergoing major, non-cardiac surgery.
"Based on these findings we need to step back and take a closer look at who should get beta blockers," he said.
The data suggest that people taking a beta blocker already should continue to take it before and after surgery, London said. Patients with two or more cardiac risk factors may benefit by receiving beta blockers before surgery, he added.
An expert not involved with the study talked about surgical risk.
"Patients undergoing non-cardiac surgery are at increased risk for cardiovascular events and death during surgery and the weeks that follow," said Dr. Gregg Fonarow, a spokesman for the American Heart Association and a professor of cardiovascular medicine and science at the University of California, Los Angeles.
Some trials and observational studies have shown that use of beta blockers reduces this cardiovascular risk, whereas other studies have shown no such benefit. As a result of the mixed data and controversy, beta-blocker use before surgery has fallen, he said.
Fonarow said the results of the new study showed a benefit for patients who remained on the drugs, while "patients receiving beta blockers before surgery, where therapy was not continued, were at twice the risk for cardiovascular mortality."
The report was published in the April 24 issue of the Journal of the American Medical Association.
For the study, London's team collected data on nearly 137,000 people who had a non-cardiac surgery at VA medical centers from January 2005 through August 2010.
Among these patients, about 33 percent had been taking beta blockers before surgery and 40 percent may have taken them after their operation.
In the hospital, nearly 67 percent of the patients who had vascular surgery were given beta blockers, compared with about 37 percent of patients who had other types of operations, the researchers found.
As patients' risk factors for heart problems increased, so did the likelihood they would be given beta blockers -- ranging from about 25 percent for those with no risk factors to 71 percent of patients with the most risk factors.
In all, about 1.1 percent of patients died in the month after surgery and 0.9 percent developed heart problems, according to the report.
Among patients who received beta blockers, the risk of dying in the 30 days after surgery was reduced by 27 percent. For those who had the most risk for heart problems, the odds of dying were reduced by 60 percent.
These risk reductions were seen only among patients who didn't have a heart operation, the researchers said.
In addition, patients receiving beta blockers had a 33 percent lower risk of developing heart problems after surgery than those who didn't get the drugs. This benefit, too, was confined to those who didn't have a heart operation, the researchers noted.
Although the study tied the use of beta blockers to better outcomes for patients undergoing non-heart surgery, it didn't prove a cause-and-effect relationship.
"Additional trials are needed to evaluate the efficacy of beta blockers for patients undergoing non-cardiac surgery," Fonarow said. "Patients receiving beta-blockers before surgery should continue on this therapy."
To learn more about heart disease, visit the American Heart Association.