Two extensive clinical trials have shown that a decades old drug remains useful for patients who have suffered a myocardial infarction, even in the context of modern treatments that can prevent permanent lesions of the cardiac muscle. However, it remains unclear whether all the patients, or only some of them, benefit from the so-called beta-blockers, which are usually prescribed to all people after a myocardial infarction, notes Reuters.
Two very contradictory studies in a certain sense were presented on Saturday at an important cardiology conference in Madrid and published in The New England Journal of Medicine.
“It is not unusual for studies to give different results,” said Dr. Borja Ibanese from Centro Nacional of Cardiovascular Investigaciones Carlos III in Madrid, who led one of the studies.
“However, it is quite unusual to see two studies with seemingly divergent results presented the same day,” he added.
Both studies have agreed on a thing
Most importantly, Ibanese said, it is the conclusion on which both teams agree, namely that beta-blockers reduce the risk combined by another heart attack, heart failure or death in patients without heart failure, but with slightly affected cardiac function.
The question is whether pills are beneficial or useless for those with normal functional heart, which represent about 80% of patients after a first heart attack.
Medications act by inhibiting epinephrine and norepinephrine hormones, thus reducing heart rate and blood pressure, reducing the working load and reducing its oxygen requirement.
Both new studies involved survivors of a heart attack whose hearts were still normal, ie the left ventricle pump at least 40% of the blood at each beat. Both studies followed patients for about 3.5 years.
But there are some differences
Among the 5,574 volunteers from the study of Betami -Danbock in Norway and Denmark, drugs have shown a clear benefit. Patients randomly distributed to receive beta-blockers had a 15% lower risk of death or major adverse cardiovascular events, especially a new heart attack, compared to patients who did not take these pills, researchers found.
However, among the 8,438 participants in the Reboot study conducted in Italy and Spain, beta-blockers had no effect on the incidence of deaths for any cause, myocardial infarction relapses or hospitalizations for heart failure, according to a separate report.
Part of the difference may be due to the fact that the patients did not receive all the same beta-blockers, and the Scandinavian patients could have been more prone to adverse events, because they were a little older than patients in Spain and Italy, and several of them had mild cardiac dysfunction, said Dr. Dan at the University of Oslo.
Among the participants in Reboot study, those taking Beta-blockers-especially those with good cardiac function that received higher doses-had more adverse results than women who did not take drugs, reported researchers in the European Heart Journal.
An uncertainty on benefits for normal -hearted patients
In Reboot study, researchers have observed a lower rate of new heart attacks, heart failure or death in patients with slightly reduced cardiac function, indicated by an “ejection fraction” of the left ventricle between 40% and 49%, taking beta-blockers.
The effect in this subgroup has been confirmed in an analysis of the data collected from Reboot, Betami-Danbock and from a Japanese study, according to a report published in The Lancet.
The message for cardiologists, said Ibanese, is “now we can confident that beta-blockers are beneficial” in patients with easily affected cardiac function and “remains reasonable uncertainty about their benefits” in patients with normal functional heart.
Atar said that an analysis that focuses specifically on the use of beta-blockers by normal cardiac patients will be presented at a US cardiology conference in November.
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