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Trial challenges the practice of using beta blockers after a heart attack

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Trial challenges the practice of using beta blockers after a heart attack

aTLANTA – Beta blockers are a mainstay of cardiovascular treatment and are often given to patients after a heart attack. But a new major study turns that convention on its head, suggesting that the drugs may not actually help many of these patients.

The study, which included about 5,000 patients who specifically had preserved ejection fraction after a heart attack, found that long-term treatment with beta-blockers did not significantly reduce the combined risk of death or another heart attack, according to results presented here Sunday at 1 p.m. the American College of Cardiology Conference and published in the New England Journal of Medicine.

Ejection fraction, the portion of blood pushed out of the left ventricle with each heartbeat, serves as a measure of the heart’s squeezing function. This study defined preserved or normal ejection fraction as greater than 50%, although some other studies define it as greater than 40%.

The frequent use of beta blockers after heart attacks is based on research conducted decades ago, before advances in the procedures doctors now use to open blocked arteries. The drugs make the heart beat slower and are intended to reduce pressure on the heart, but they can have side effects, such as fatigue, weight gain and sexual dysfunction.

Today, patients are having smaller heart attacks with less cardiac damage, leaving doctors wondering whether current guidelines, which recommend the use of beta blockers regardless of ejection fraction, are still useful. Observational studies have suggested that beta blockers may not be helpful for people with preserved ejection fraction, but the field has until now lacked large randomized trials looking at this question.

“This is one of those studies at ACC that I think has the potential to change practice,” said Kim Eagle, director of the University of Michigan Frankel Cardiovascular Center, who was not involved in the study. It is “a very important landmark study that will change the way patients are currently treated [heart attacks] to be taken care of.”

The study mainly involved patients from Sweden, but also some from Estonia and New Zealand. The researchers followed patients for an average of three and a half years.

Patients taking beta blockers had a 4% lower combined risk of death or another heart attack compared with patients not taking the drugs, but this result was not statistically significant.

People taking beta blockers also did not have a significantly lower risk of the individual outcomes studied: death from any cause, death from cardiovascular causes, heart attack, hospitalization for atrial fibrillation, and hospitalization for heart failure.

The number of events examined for safety – such as stroke, low blood pressure and fainting – was similar between the two groups.

The researchers did see that a subgroup of people who were already taking beta blockers after a heart attack and then had to take beta blockers in the trial had a higher risk of death or another heart attack, but the authors said this was likely. a false finding.

“This is only a subgroup analysis that has no statistical power and there is no plausible explanation in our study. That’s why we believe it’s a game of chance,” says Troels Yndigegn, lead author and interventional cardiologist at Lund University in Sweden. said via email.

The patients who were not taking beta blockers did not receive a placebo drug, so it was not a blinded study. That may have introduced bias, but the authors said it is unlikely to have affected the hard outcomes of death, heart attacks and hospital admissions that were studied.

There are also limitations to the extent to which this study is generalizable, as it mainly involves patients from Sweden, says Anuradha Lala-Trindade, an advanced heart failure and transplant cardiologist at Mount Sinai in New York, who was not involved in the trial.

Furthermore, only 22.5% of study participants were female. Historically, there has been an underrepresentation of women in cardiovascular research. Yndigegn, the lead author, said: “our study has a similar proportion of female patients as in other similar materials.”

It remains to be seen how physician groups and guideline writers respond, but “I applaud the authors and the researchers because it takes courage to question old dogma,” Lala-Trindade said. “We’re in a very different era and the patient population is very different as well, so it really begs the question of what we should accept and what we should retest.”

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