A shadow of doubt has been cast over the widespread use of beta-blockers, after research published in the Journal of the American Medical Association questioned their effectiveness in some patients.

Beta-blockers, which slow heart rate and lower blood pressure, have long ruled over the management of patients with coronary artery disease (CAD), particularly after a patient has suffered a heart attack as they can help ward off another.

But the researchers - lead by Sripal Bangalore, of the NYU School of Medicine, wanted to explore the policy for their continued long-term use as, they claim, it is based on older clinical data and fails to take into account recent innovations in the field. 

Analysing data from more than 44,700 patients who had either suffered a prior heart attack (31%), had CAD without a heart attack (27%), or had CAD risk factors (42%), they found that beta-blockers had little effect on the risk of subsequent heart attacks and stroke over a 44-month period.

Taking a closer look, the research found that 12.9% of people with CAD (without heart attack) taking beta-blockers died from heart disease or had a heart attack or a stroke (the primary outcome), but this was not much different to the 13.6% of those not taking the therapy.

In the prior heart attack group, the event rates were also not significantly different among those who took beta-blockers (16.9%) and those who didn't (18.60%).

In the risk factors alone group, event rates were actually higher in those with beta-blocker use (14.2%) versus those without (12.1%) for the primary outcome, while the former group was also found to be at higher risk of death or hospitalisation for a cardiac procedure.

On the plus side, patients treated with beta-blockers following a recent heart attack did seem to have a lower risk of being hospitalised, the data indicate.

Further research needed

All-in-all, the researchers concluded that "beta-blocker use was not associated with a lower event rate of cardiovascular events at 44-month follow-up, even among patients with prior history of [heart attack]", but also noted that "further research is warranted to identify subgroups that benefit from beta-blocker therapy and the optimal duration of beta-blocker therapy".  

Commenting on the findings, Steven Nissen, head of the Department of Cardiovascular Medicine at the Cleveland Clinic Foundation, also said a "controlled trial will be necessary to change guidelines for prescribing beta blockers", according to ABC News.

"Abandonment of this type of therapy for post-MI [post-heart attack] patients based upon an observational study is not warranted," he stressed.