Patients with mild heart failure live longer if they’re treated with advanced defibrillators that synchronize the beating of the heart in addition to shocking it back into rhythm when it stops, a study found.

The trial, presented today at the American College of Cardiology meeting in Washington, is the first to show a significant survival benefit in people with few or no symptoms. The findings may expand the $3 billion market for cardiac resynchronization, or CRT, devices from Boston Scientific Corp. (BSX), Medtronic Inc. and St. Jude Medical Inc. that are now recommended for patients with more advanced disease.

About 5 million Americans suffer from heart failure, when a weakened and enlarged heart can’t pump enough oxygen-rich blood to fuel the body. The disease worsens over time and is the leading cause of hospitalization, and return hospital trips, in Medicare. Slowing the disease is key, said Robert Bonow, professor of cardiology at Northwestern University’s Feinberg School of Medicine.

“CRT is underutilized even in patients with severe symptoms,” Bonow, who wasn’t involved in the research, said in an interview. “This is a reawakening for everybody that CRT is a device that can improve symptoms and improve survival if we use it in the right patients. We are seeing that even patients with mild symptoms benefit if we identify them correctly.

Targeted Therapy

The researchers identified the patients most likely to respond based on results from a standard EKG, which tracks the electrical pattern of the heart.

The finding was notable because those with a defect in the way electricity moves through the heart had a survival benefit, while those with a different problem may have been harmed by the therapy.

‘‘We now have an intervention that can potentially change the outcomes for certain heart failure patients,’’ said Ilan Goldenberg, the lead researcher on the study and director of cardiology at Leviev Heart Center in Ramat-Gan, Israel. ‘‘We can intervene early in the course of the disease to reduce the risk of long-term mortality.’’

To assess which patients should get the resynchronization devices, doctors had been looking at the amount of time it takes for electricity to move through the heart, not the reason for it, Bonow said.

‘‘Now we realize it’s the cause of the electrical dysfunction that matters, not the amount of time it takes for the electrical current to move all the way through the heart,’’ he said.

Different Conditions

Those with an electrical malfunction known as a left-bundle branch block were 40 percent less likely to die after an average of seven years than those given a standard defibrillator that simply shocks a stopped heart, in the study. Patients without the condition were 57 percent more likely to die if they received the resynchronization device.

‘‘There is a subset of those patients who may benefit from this therapy, improve how they feel, keep them out of the hospital and, even if they are feeling well, help them live longer,’’ Bonow said. ‘‘Patients with heart failure should be asking their doctors if they are a candidate for this.’’

The study, funded by Natick, Massachusetts-based Boston Scientific, was simultaneously published in the New England Journal of Medicine. Medicare is the U.S. health plan for the elderly and disabled.

To contact the reporter on this story: Michelle Fay Cortez in Minneapolis atThis email address is being protected from spambots. You need JavaScript enabled to view it.

To contact the editors responsible for this story: Reg Gale at This email address is being protected from spambots. You need JavaScript enabled to view it. Andrew Pollack