Analyzing an international registry of 44,708 patients with heart disease or at risk of developing it, a team of researchers compared patients who took the drugs with those who did not and found no difference in their rates of heart attack, stroke or death related to cardiovascular problems.
“This confirms my intrinsic suspicion,” said Dr. P.K. Shah, director of cardiology at Cedars-Sinai Heart Institute, who was not involved in the study.
Beta adrenergic blockers have long been among the bestselling drugs. They counteract the effects of adrenaline, slowing the heart and lowering blood pressure. The first beta blockers were approved more than four decades ago for heart-related chest pain, but the list of approved uses grew to include hypertension, arrhythmia, migraines and heart failure.
Those uses are not questioned in the current study, published this week in the Journal of the American Medical Association.
Some beta blockers are approved for treatment of patients after heart attacks, based on several studies suggesting that they prevent subsequent attacks. Extrapolating from that data, doctors also began prescribing the drugs for heart disease patients who had never suffered heart attacks as well as for patients merely at risk for heart disease — uses that have never been rigorously tested.
Most of the studies showing a protective effect in heart attack victims were conducted before the advent of modern interventions for cardiovascular disease, including the widespread use of aspirin, cholesterol-lowering statin drugs and procedures to open blocked blood vessels. Those developments raised the question of whether it was still scientifically justified to use beta blockers in such a wide range of patients, said Dr. Sripal Bangalore, a New York University cardiologist and lead author of the new study.
In the registry, which enrolled patients in 2003 and 2004 and followed them until 2009, 67 percent of those with prior heart attacks were on beta blockers, along with 57 percent of those with heart disease but no history of attacks and 26 percent considered at risk for developing heart disease. Within each group, the researchers compared the outcomes of patients taking the drugs with those who were not, controlling for a variety of factors, including age and medical history.
Even among the 9,451 patients with prior heart attacks, there was no statistically significant difference between the groups: 16.9 percent on beta blockers died or suffered a stroke or another attack, compared with 18.6 percent of those not taking the drugs.
Shah, of Cedars, predicted that the study could spur doctors to change the way they prescribe the drugs.
But Dr. Gregg Fonarow, a cardiologist at the University of California, Los Angeles, who also played no part in the study, said the evidence was too weak to offer doctors any guidance. Only a controlled clinical trial could do that.
“Observational research like this is never definitive or the final word,” he said.
Bangalore agreed that a clinical trial would provide stronger evidence. Still, he said he planned to cut back on the use of beta blocks “in patients who have never had a heart attack.”
A clinical trial would answer other questions as well. There are at least 13 varieties of beta blockers, each with its own set of approved uses. The study did not address whether some pills might be more effective than others, or whether certain subgroups of patients might benefit from the drugs.
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