Unnecessary use of beta-blockers after a heart attack

Today, when patients are discharged from hospitals after an acute heart attack, they are regularly treated with beta-blocker drugs such as metoprolol and bisoprolol. Now new research shows that about half of them do not benefit from the treatment and should not receive it at all. These are the patients who have suffered a small heart attack and have retained heart function afterwards. The study will change the way patients are treated in the future, says the lead researcher and last author of the study, Professor Tomas Jernberg from the Department of Clinical Sciences at Karolinska Institutet.

”I am convinced that this will influence future practice. This study has already been mentioned in the European guidelines for cardiac care, so the results are in demand," he says.

The project was led by researchers at Karolinska Institutet, Lund University and Uppsala University. More than 5,000 patients at 45 hospitals in Sweden, Estonia and New Zealand who suffered a small heart attack were randomized to either receive or not receive beta-blockers at discharge.

The study began in September 2017 and patients were followed up until November 2023, by which time 7.9 percent of those receiving beta-blockers had the primary outcome of death or a new heart attack, compared to 8.3 percent of those not receiving beta-blockers. This difference is not statistically significant. Nor was there any difference between the groups in the secondary outcomes.

The result means that, unusually, the drug treatment becomes simpler and cheaper for all parties, says Tomas Jernberg.

”Typically, new research results in the addition of a medication to a patient's regimen. However, this study shows that patients will benefit from taking one fewer drug”.”

But he immediately warns patients not to stop their treatment on their own accord. The current study is only about the effect of starting treatment after a small heart attack, not after a larger one. Nor does it show anything about the effects of stopping treatment. More importantly, stopping medication should always be done in consultation with the treating physician.

”This is for several reasons. There may be other causes, other diagnoses, behind the use of beta-blockers. Then there is the fact that if you are going to stop, you should stop beta-blockers gradually. If you do it too quickly, you can get some heart palpitations and other discomfort. So, it is very important that you talk to your doctor before stopping any heart medication," says Tomas Jernberg.

The research was funded by the Swedish Research Council and the Swedish Heart-Lung Foundation. The researchers report that there are no conflicts of interest.

Publication: "Beta-blockers after Myocardial Infarction and Preserved Ejection Fraction" Troels Yndigegn, Bertil Lindahl, Katarina Mars, Joakim Alfredsson, Jocelyne Benatar, Lisa Brandin, David Erlinge, Ola Hallen, Claes Held, Patrik Hjalmarsson, Pelle Johansson, Patric Karlström, Thomas Kellerth, Toomas Marandi, Annica Ravn-Fischer, Johan Sundström, Ollie Östlund, Robin Hofmann, Tomas Jernberg. New England Journal of Medicine, online April 7, 2024.

Facts:

In Sweden, around 20,000 people have a heart attack every year. Half of them have a small heart attack with retained heart function afterward. This means that the heart can still pump out more than 50 percent of the volume in the left chamber of the heart, known as preserved left ventricular systolic function.

The reasons behind the current practice of giving everyone a beta-blocker after a heart attack can be traced back to the 1980s when studies showed unequivocally that it was beneficial. But since then, other cardiovascular treatments have improved, as have diagnostics, so doctors are now detecting many of the heart attacks that were never classified as infarctions before. This, together with the fact that the incidence of heart attacks has steadily declined since the 1980s, means that today's heart attacks are generally smaller and with a higher proportion of people with preserved left ventricular function.

Source: Tomas Jernberg.