MINNEAPOLIS — Botulinum toxin, widely embraced as the wrinkle-remover Botox, appeared also to wipe out a common and potentially deadly heart rhythm problem that can occur after open-heart surgery.

In a small study of heart bypass patients, surgeons injected the paralyzing toxin into fat pads that can build up around the heart. The results, which cut down on clot-causing heart rhythm problems, could have broader implications for about 2.7 million people in the United States with what is known as atrial fibrillation.

The idea isn’t as radical as it sounds. The fat pads are active, producing hormones and cytokines and increasing the risk of atrial fibrillation. Surgeons sometimes target them when doing procedures to sear away errant electrical signals that can trigger the condition. A shot with Allergan’s Botox or a rival drug from Merz Pharma may be an even more effective and efficient therapy, doctors said.

“This has huge implications,” said John Day, director of heart rhythm services at Intermountain Medical Center in Salt Lake City and president-elect of the Heart Rhythm Society. “For wrinkles, Botox is not permanent,” Dr. Day said. “This study is suggesting a permanent effect, because at one year there is still not any atrial fibrillation.”

The potential size of the market underscores the variety of benefit from the toxin, which was first approved in the United States in 1989 for vision problems and is now used for eight medical conditions in addition to wrinkles. Botox, a highly purified form of the neurotoxin produced by the botulinum bacterium, is now a blockbuster drug and produced revenues of $2.23 billion last year for Allergan. The drug was a major attraction for Actavis, which beat out Valeant Pharmaceuticals International to buy Allergan in a $66 billion deal last year.

The trial was the first time the technique has been tried in humans, and Dr. Day said the results need to be confirmed in a second trial. If they are, the approach could completely change the way doctors manage the problem of atrial fibrillation. Currently, about one-third of people who undergo open heart surgery develop atrial fibrillation, which can slow recovery and lead to complications including stroke and heart failure.

The study was presented at the Heart Rhythm Society’s annual meeting in Boston. In 30 patients who got four injections in the fat pads around the left ventricle, the heart’s main pumping chamber, they showed no signs of the atrial fibrillation as long as a year later. A comparison group given saline injections found that seven of the 30 patients, or 27 percent, had recurrent atrial fibrillation. There were no complications from the injections, which added about 11 minutes to the surgeries.

Along with preventing atrial fibrillation, the treatment didn’t cause other problems with the heart’s rhythm, said Evgeny Pokushalov, lead author and chief of interventional cardiology at the State Research Institute of Circulation Pathology in Novosibirsk, Russia. While the drug typically only works for a few months, the time may allow the heart to recover and normalize after surgery, he said.

The researchers used the drug Xeomin from Germany’s Merz Pharma, which they purchased themselves. They are planning a larger study involving numerous hospitals, and perhaps corporate support, in the future, Dr. Pokushalov said. If the results are confirmed, the medicine may be widely used, he said.

“If we can prove this, 100 percent of patients who are undergoing some open-heart surgery or another procedure will receive this therapy,” he said. “If this can protect patients, it can be made into the future gold standard of treatment.”