With each heartbeat, the left ventricle propels oxygen-rich blood into the aorta to be distributed to nearly every tissue in the body. The efficiency of this chamber of the heart is routinely assessed in clinical settings, with a measurement called left ventricular ejection fraction (LVEF), which assesses the damage after a heart attack. Since the 1980s, the standard of care after myocardial infarction (a heart attack) has been to administer beta-blockers — medications which soften the effects of adrenaline, slowing heart rate and relaxing blood vessels. Even patients with a preserved LVEF (50% or greater) receive them. Since the development of modern myocardial infarction treatments, mortality rates have declined dramatically, indicating that this approach is effective. But for some scientists, effective doesn’t necessarily mean optimal. Earlier this year, a team of researchers published a study in the New England Journal of Medicine that challenges the routine use of beta-blockers, suggesting that they might not be necessary for all patients.

The team conducted a meta-analysis of five clinical trials that assigned heart attack patients with preserved LVEF to either receive or not receive beta-blocker therapy. In total, 17,801 patients were included: 8,831 (49.6%) of those patients were assigned to receive beta blockers, while 8,970 (50.4%) were in the no-beta-blocker group. In the time following their heart attack, 335 patients in the beta-blocker group died, compared to 326 patients in the no-beta-blocker group. Of those deaths, those that were cardiac-related occurred at similar rates — nearly the same between the beta-blocker and no-beta-blocker groups. To no surprise, occurrences of heart failure followed suit, happening in about the same number of patients from both groups. After accounting for factors such as age, sex, and cardiovascular history, each comparison resulted in that same conclusion: patients with preserved LVEF and no other indication for the medication seem to gain no benefit from beta-blocker therapy.

Of course, no benefit doesn’t necessarily mean that beta-blockers hurt the prognosis of patients with preserved LVEF. What’s the incentive to change medical tradition? While beta-blockers save lives, they aren’t completely harmless. Patients are at risk of a variety of side effects, like exercise intolerance and hypotension. Aside from a better quality of life, individuals with preserved LVEF also stand to experience a lower medication and financial burden.

Current treatment for myocardial infarction has been reinforced through decades of research and clinical application. A handful of studies with a population of 17,000 people isn’t enough to change the standard of care — in the US alone, over 800,000 people experience a heart attack each year. Even among patients with preserved LVEF, residual ischemia or a high resting heart rate could persist, things that could easily respond to beta-blockers. Still, the meta-analysis stands to upend long-standing clinical assumptions, something that’s incredibly hard to do in medicine. It also highlights the power of the left ventricle: small changes in its function can result in completely different clinical outcomes.