For decades, beta blockers have been prescribed as a routine treatment for patients after a heart attack. Now, groundbreaking new research suggests that for millions of patients, these drugs may be providing no benefit — and, for women, potentially increasing risk.
The results come from the REBOOT Trial, the largest clinical study ever conducted on this question. Findings were presented on August 30 at the European Society of Cardiology (ESC) Congress 2025 in Madrid and published simultaneously in The New England Journal of Medicine.
What the REBOOT Trial Found
The REBOOT study enrolled 8,505 patients across 109 hospitals in Spain and Italy who had experienced an uncomplicated heart attack but retained normal heart function. Patients were randomly assigned to receive beta blockers or no beta blockers, while all received standard modern treatments such as stents, statins, and antiplatelet therapy.
After nearly four years of follow-up, researchers found:
-
No significant difference between patients who received beta blockers and those who did not in terms of death, recurrent heart attack, or hospitalization for heart failure.
-
For women, beta blocker use was associated with a 2.7% higher absolute risk of death and increased rates of adverse cardiovascular events.
-
Men did not experience the same elevated risks.
“This trial will reshape all international clinical guidelines,” said Dr. Valentin Fuster, President of Mount Sinai Fuster Heart Hospital and senior investigator of the study. “It represents one of the most significant advances in heart attack treatment in decades.”
Why This Matters: A 40-Year-Old Standard Challenged
Beta blockers became standard therapy after heart attacks in the 1980s, when studies showed they lowered the risk of sudden death from arrhythmias and reduced strain on the heart. But those studies were conducted before today’s life-saving advances in cardiology:
-
Rapid revascularization (angioplasty and stenting) drastically reduces heart muscle damage.
-
Statins, ACE inhibitors, and antiplatelet drugs are now widely used, further lowering risks.
“In the modern era, where arteries are reopened quickly and heart damage is smaller, the need for beta blockers is unclear,” said Dr. Borja Ibáñez, principal investigator and CNIC’s Scientific Director. “REBOOT was designed to rigorously test whether they are still necessary — and the results are clear: they are not.”
Women Face Higher Risks With Beta Blockers
Perhaps the most striking result was seen in women. A substudy, published in the European Heart Journal, revealed that women with completely normal heart function after a heart attack who were prescribed beta blockers faced:
-
A higher risk of mortality
-
Greater likelihood of hospitalization for heart failure
-
Increased chance of experiencing another heart attack
This elevated risk was not observed in men or in women with slightly reduced heart function.
“This is a powerful reminder that sex-specific differences in medicine matter,” said Dr. Ibáñez. “What benefits men may harm women.”
Implications for Patients and Doctors
Currently, over 80% of patients with uncomplicated heart attacks are discharged from hospitals with a beta blocker prescription. The REBOOT trial suggests that millions may be taking these drugs unnecessarily — and in some cases, dangerously.
Side effects of beta blockers include:
-
Fatigue and dizziness
-
Bradycardia (low heart rate)
-
Sexual dysfunction
-
Reduced exercise capacity
“By eliminating unnecessary prescriptions, we can improve patient quality of life and reduce risks,” said Dr. Fuster.
A Shift in Global Guidelines
The REBOOT findings are expected to transform heart treatment guidelines worldwide. Experts say medical societies in the US, Europe, and Asia will now likely recommend against prescribing beta blockers to patients with preserved heart function after a heart attack — unless another clear indication exists, such as arrhythmia or high blood pressure.
This follows a string of other paradigm-shifting trials led by CNIC and Mount Sinai, including:
-
SECURE Trial: A “polypill” combining aspirin, ramipril, and atorvastatin reduced cardiovascular events by 33%.
-
DapaTAVI Trial: Diabetes drugs dapagliflozin and empagliflozin improved outcomes in patients undergoing aortic valve replacement.
“Medicine evolves,” said Dr. Ibáñez. “It’s not enough to test new drugs; we must also question whether old ones are still necessary.”
Key Takeaways for Patients
-
If you have had a heart attack and have normal heart function, beta blockers may no longer be necessary.
-
Women in particular may face higher risks if prescribed these drugs.
-
Patients should not stop taking medication on their own but should speak with their cardiologist about whether beta blockers are still appropriate.
“This trial helps simplify treatment, cut unnecessary side effects, and tailor therapy to today’s medical realities,” said Dr. Fuster.
