A new study on the effects of beta blockers and surgical procedures reveals that patients given a beta blocker—beta blockers are a type of blood pressure drug—to reduce heart risks prior to surgery, were one-third more likely to die within a month and also had double the risk of stroke compared with those who received a placebo, or a dummy pill. The Canadian study appears in the journal, Lancet. The study is the largest, most rigorous to date that reviews the effects of beta blockers in reducing surgery-related risks; other, smaller studies provided mixed results. “There is a real potential that beta blockers are causing serious harm in the surgical setting,” said Dr. P.J. Devereaux of McMaster University in Ontario, who conducted the study. “If my mother was undergoing surgery and given a beta blocker, I would be extremely upset based on this evidence,” Devereaux added.
It has been long believed that taking a beta blocker prior to major surgery protects the patient from heart risks related to the surgery’s stress. These new findings challenge that theory. Surgery often raises levels of a stress hormone known as catecholamine. Catecholamine increases pressure and heart rates. “Beta blockers block the effects of increased catecholamines, so the physiological rationale would say they would be beneficial to people,” Devereaux said.
Devereaux and colleagues tested this idea, studying over 8,000 patients in 23 countries at 190 hospitals who were undergoing major surgery unrelated to the heart. Those studied had or were at risk for clogged arteries. Half were given the beta blocker metoprolol—sold by AstraZeneca as Toprol XL—two to four hours before and 30 days following surgery. The other half received a placebo.
The doctors were looking for heart complications such as heart-related death, non-fatal heart attacks, or a heart-stopping event known as cardiac arrest in which the person survived. The study revealed that those who took the drug had fewer heart attacks and abnormal heart rhythms; however, they were more likely to die or have a stroke. For every 1,000 people with similar risks undergoing non-cardiac surgery, the drug could prevent 15 people from experiencing heart attack, three from requiring a shock to restore a normal heartbeat, and seven from developing a type of heart rhythm known as atrial fibrillation.
That said, eight more people would die, five would have a stroke, 53 percent would have abnormally low blood pressure, and 42 percent would have an abnormally slow heart beat. “This is an important study because, although the beta blocker reduced the number of heart attacks that occurred following surgery, it caused more strokes, thus—on balance—causing more harm than good,” Peter Weissberg, medical director of the British Heart Foundation, said. “This is why it is so important to undertake large clinical trials rather than assuming drugs will only do what is expected of them,” Weissberg added.
Devereaux, initially presented his findings at the November American Heart Association meeting and expects this study to create debate over the wisdom around patients taking beta blockers prior to a major surgery. “It is telling us something we didn’t realize in the past,” he said.
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