A landmark clinical trial has upended decades of standard cardiac practice, finding that beta blockers, routinely prescribed to millions of heart attack survivors, provide no meaningful protection for patients whose hearts recover normal function and may even pose risks for women.
The REBOOT trial, published in The New England Journal of Medicine, enrolled 8,505 patients from 109 hospitals across Spain and Italy. Researchers randomly assigned patients to either take beta blockers or skip them after hospital discharge, while everyone received other standard modern therapies. Over nearly four years of follow-up, beta blockers did not significantly reduce death, repeat heart attacks, or hospitalizations for heart failure in patients with preserved heart function.
The finding challenges what has been automatic medical practice since the 1980s. Today, more than 80 percent of patients with uncomplicated heart attacks leave the hospital on beta blockers, a tradition born when cardiac care looked vastly different. Back then, blocked arteries often went unopened and patients had few other treatment options. Now, doctors quickly restore blood flow through modern interventions and combine those with powerful statins, antiplatelet medications, and other evidence-based drugs that simply did not exist decades ago.
"This trial will reshape all international clinical guidelines," said Valentin Fuster, the study's senior investigator and president of Mount Sinai Fuster Heart Hospital. The results suggest that for many patients, an entire medication they have been taking may be unnecessary.
Beta blockers work by slowing the heart rate and reducing the oxygen demands on cardiac muscle, a mechanism that made clear sense when hearts were severely damaged by blocked arteries. But in today's world of rapid artery reopening, the extent of heart damage is often far smaller. Principal investigator Borja Ibáñez noted that beta blockers were originally added to treatment regimens because they significantly cut mortality at the time, yet that original rationale may no longer apply.
Beyond their lack of benefit, these drugs carry real downsides. Beta blockers commonly cause fatigue, abnormally low heart rates, and sexual dysfunction. For patients already juggling multiple medications, eliminating an unhelpful drug could simplify treatment, reduce side effects, and improve quality of life.
A substudy published in the European Heart Journal uncovered a more troubling signal: women who received beta blockers faced a higher risk of death, heart attack, or heart failure hospitalization compared with women who did not. Men showed no such increased risk. Among women with completely normal heart function, those on beta blockers faced a 2.7 percent higher absolute risk of mortality over 3.7 years. Women with mildly reduced heart function did not show this excess danger.
The sex-specific finding suggests that one-size-fits-all prescribing after heart attack needs to give way to decisions tailored to individual patients and risk profiles. That approach fits a broader shift in cardiology away from simply adding more medications and toward asking which treatments genuinely matter for today's patients.
The REBOOT findings are not entirely isolated. The REDUCE-AMI trial, published in 2024, reached similar conclusions about patients with preserved heart function. However, the picture becomes more nuanced for other groups. The BETAMI-DANBLOCK trials, also presented at the European Society of Cardiology Congress in 2025, found that beta blockers did reduce combined death and major cardiovascular events in selected heart attack patients with preserved or mildly reduced function.
A meta-analysis of individual patient data helped clarify the pattern. For patients with normal heart function, defined as a left ventricular ejection fraction of at least 50 percent, beta blockers did not reduce death, heart attack, or heart failure. But patients with mildly reduced function, with an ejection fraction of 40 to 49 percent, may still benefit from the drugs.
This emerging consensus suggests beta blockers will remain important for many patients, particularly those with reduced heart function or other medical reasons to take them. But for the large group of patients who recover from uncomplicated heart attacks with normal pumping ability, routine prescription is now under serious scrutiny. The trial received no funding from pharmaceutical companies, ensuring the findings reflect pure scientific inquiry rather than industry interests.
Author Jessica Williams: "After forty years of unquestioned use, it takes courage to test whether a standard treatment still makes sense, and this trial proves that even the most entrenched practices deserve rigorous reexamination."
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