Experts report at least 800,000 deaths worldwide have been caused by drugs used to cut the risk of a heart attack—beta-blockers—after surgery. Those taking beta blockers, which have been prescribed in the treatment of heart disease since the 1970s, are one-third more likely to die within a month of surgery and twice as likely to suffer a stroke, a study found.
Dr. P.J. Devereaux, a cardiologist and epidemiologist at McMaster University in Hamilton, Canada was the study’s lead researcher. The research was published in the Lancet and stated beta-blockers cost more lives than they saved and their use in surgery patients was based on inadequate research. 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 Devereaux.
Guidelines established in 1996 by the American College of Cardiology recommend beta-blockers be used in all but cardiac surgeries. Although adopted worldwide, Devereaux claimed that these guidelines were based on the findings of two small studies saying, “On a conservative estimate, if 10 percent of physicians acted on the guidelines in the last decade, it would suggest that 800,000 people died unnecessarily and half a million had major strokes.” Worldwide, about 100 million adults undergo non-cardiac surgery annually; one million suffer major complications.
Devereaux and colleagues studied 8,351 patients in 23 countries at 190 hospitals who underwent major non-cardiac surgery. 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. Those given the drugs were one-third more likely to die in the month after surgery, risk of death increased from 2.3 to 3.1 percent. They were also twice as likely to have a stroke, doubling their risk from 0.5 to one percent. The results suggest that for every 1,000 patients undergoing non-cardiac surgery, beta-blockers would prevent 15 from having a heart attack; however, at least eight would die and five would suffer a stroke. The drugs would also lead to abnormally low blood pressure in over half such patients; four in 10 would suffer an abnormally slow heartbeat.
“Surgery is a stressful event and if the patient goes into a shock state, their blood pressure can drop very low,” said Devereaux. “Beta blockers keep blood pressure low and it looks like the combined effect could mean patients can’t sustain adequate blood pressure to survive, or to avoid having a stroke,” Devereaux added. Professor Peter Weissberg, the medical director at 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. The results of this trial—of a relatively high dose of a beta blocker given before surgery—do not mean patients stabilized on long-term beta blocker therapy will be at increased risk if they have surgery.”