Two major studies disagreed over the impacts of beta blockers for heart attack patients.
Beta blockers slow heart rates and are considered a key treatment for heart patients. But they are very old drugs, and lack evidence from modern, multi-thousand-subject randomized controlled trials.
One paper looked at 5,574 people in Scandinavia, and found a notable 15% reduction in deaths and major cardiovascular events among people whose heart function was back to normal after the attack, but another, announced the same day and looking at 8,438 patients in Spain and Italy, found no impact.
Both studies found benefit for patients with impaired heart function. The exact details matter: About 10% of the US population is on beta blockers.