A decades-old class of drugs, beta-blockers, continues to help heart attack patients even in the era of modern treatments that prevent long-term heart muscle damage. Two large trials have confirmed their value, though questions remain about which patients benefit most.
Mixed Results from Two Major Trials
On Saturday, researchers presented two contradictory reports at a cardiology meeting in Madrid, later published in The New England Journal of Medicine. Dr. Borja Ibanez of Centro Nacional de Investigaciones Cardiovasculares Carlos III, who led one of the trials, noted, “It is not unusual for trials to yield different results. What is somewhat uncommon is to see two apparently divergent findings presented on the same day.”
Despite the differences, both studies agreed that beta-blockers reduce the combined risk of another heart attack, heart failure, or death in patients with mildly impaired heart function but without full-blown heart failure.
Uncertainty for Patients with Normal Heart Function
The key question is whether beta-blockers benefit patients whose hearts function normally after a first heart attack. This group represents nearly 80% of cases.
Beta-blockers, produced by companies such as Novartis, Pfizer, Abbott, Sun Pharma, and Lupin, work by blocking the hormones epinephrine and norepinephrine. As a result, they slow the heart rate, lower blood pressure, reduce cardiac workload, and decrease oxygen demand.
BETAMI–DANBLOCK Trial: Clear Benefits
The BETAMI–DANBLOCK study from Norway and Denmark followed 5,574 heart attack survivors for 3.5 years. All participants had a left ventricular ejection fraction (LVEF) of at least 40%. Results showed that patients taking beta-blockers had a 15% lower risk of death or major cardiovascular events, particularly repeat heart attacks, compared to those not on the drugs.
REBOOT Trial: No Overall Benefit
In contrast, the REBOOT trial conducted in Italy and Spain tracked 8,438 patients for a similar period. This trial found no significant effect of beta-blockers on overall death, repeat heart attacks, or hospitalization for heart failure.
Researchers suggested that differences in patient characteristics and drug regimens might explain the contrast. Scandinavian patients were slightly older and more likely to have mild heart dysfunction, which could have amplified the benefits of beta-blockers.
Gender Differences Raise New Questions
Interestingly, the REBOOT study reported that female participants with good heart function, particularly those on higher doses of beta-blockers, experienced more adverse outcomes than women not on the drugs. This finding, published in the European Heart Journal, calls for further investigation.
Evidence Stronger for Mildly Reduced Heart Function
Despite inconsistencies, both trials confirmed that patients with mildly reduced heart function (LVEF between 40% and 49%) benefited from beta-blockers. A pooled analysis of REBOOT, BETAMI–DANBLOCK, and a Japanese trial, published in The Lancet, reinforced this conclusion.
What This Means for Cardiologists
Dr. Ibanez emphasized, “We can now state with confidence that beta-blockers are beneficial in patients with mildly impaired heart function. However, there remains reasonable uncertainty about their benefit in patients with normally functioning hearts.”
Dr. Dan Atar of the University of Oslo, who led the BETAMI–DANBLOCK trial, confirmed that more answers are coming. An upcoming analysis focusing specifically on patients with normal heart function will be presented at a U.S. cardiology meeting in November.