Now, some researchers are having a change of heart.
A new study appearing in tomorrow's issue of the Journal of the American Medical Association has found that not only are beta blockers safe for patients about to undergo coronary artery bypass surgery, but they might actually improve the outcomes.In this study, patients who received beta blockers before surgery had a 30-day mortality rate of 2.8 percent, compared to 3.4 percent for those patients who did not receive the drugs.
The patients in the beta-blocker group also experienced few side effects, spent less time on mechanical ventilation after surgery, and had fewer post-operative kidney problems.
The study was conducted by researchers at Duke University Medical Center, Louisiana State University Health Sciences Center and the Society of Thoracic Surgeons.
While not everyone agrees this study provides the definitive answer on whether beta blockers should be routinely used before bypass surgery, it is an important addition to the literature.
"At the very least, we can say that the use of beta blockers in virtually all patients coming into coronary bypass surgery is safe, and in the vast majority it's clearly beneficial," says lead author Dr. T. Bruce Ferguson Jr., a professor in the departments of surgery and physiology at LSU Health Sciences Center in New Orleans.
Ferguson and his colleagues also concluded that all patients scheduled for the surgery -- except for a subset that has a significant depression of heart function -- should receive beta blockers as a matter of course.
In 1999, about 60 percent of bypass patients received beta blockers, up from 50 percent in 1996. The surgery is performed some 570,000 times annually in the United States, and the researchers estimate that taking the drugs could save about 500 lives every year.
Part of the reason for the change in thinking is the emergence of new and improved beta blockers. Today, beta blockers are more selective, and are less often associated with significant drops in heart rate and blood pressure.
These latest findings are part of a trend toward wider use of the medication.
"Every time we've looked to see if beta blockers would work in certain subsets of patients who were previously considered to be candidates, they turned out to be beneficial," Ferguson says, referring to patients with acute myocardial infarction, some forms of unstable angina and hypertension.
The researchers aren't sure why beta blockers have this beneficial effect, but feel they may help control the body's response to the stress of surgery.
There are some limitations. This study was a retrospective analysis of 629,877 patients included in the National Adult Cardiac Surgery Database who had undergone bypass surgery at one of almost 500 hospitals in the United States and Canada between 1996 and 1999. As such, the conclusions are not considered definitive.
"It's an uncontrolled study and they were not able to control for many factors, so it's actually very difficult to determine the extent of benefit that was seen," says Dr. Stephen Gottlieb, a professor of medicine at the University of Maryland School of Medicine.
"The benefit seen in the study was not very large and in the sickest patients -- the ones whom you'd really like to see benefit -- wasn't actually seen at all," Gottlieb adds. "There are definitely notes of caution. I'm not trying to say beta blockers shouldn't be used; I am saying this doesn't actually prove they should be used."
The study authors agree that a national, randomized trial is the next step, something which is under way and should provide results in the fall.
What To Do
For more information on beta blockers, visit the American Heart Association or read this article from the American Academy of Family Physicians on the importance of the drugs in the treatment of heart failure.
The American Heart Association also has information on coronary artery bypass surgery.