Novel Pacemaker Resynchronizes Failing Hearts
March 20, 2001 (Orlando, Fla.) -- A new pacemaker device that resynchronizes the beating heart so that both chambers work efficiently is the first effective treatment for a type of heart failure that affects about 750,000 Americans, according to research presented here Tuesday at the American College of Cardiology meeting.
"After just six months with the special pacemaker, 69% of the patients had a significant improvement in quality of life," William Abraham, MD, tells WebMD. Abraham headed up the MIRACLE, meaning Multicenter InSync Randomized Clinical Evaluation, trial. He says that means the difference between being bedridden, struggling to breathe, or being "able to accomplish most activities of daily living."
Normally, the two atria and two ventricles work together, contracting and relaxing to pump blood out of the heart. But in people with heart failure, the heart no longer pumps efficiently. As a result, the heart enlarges and struggles to do its work. Symptoms include difficulty breathing, fluid retention, and extreme fatigue. About 5 million Americans have congestive heart failure, and the number continues to grow because risk increases with age.
About one in four people with severe heart failure also has a faulty electrical system that causes a type of irregular heartbeat in which the right and left sides of the heart are out of sync, like a grandfather clock that ticks when it should tock. None of the current heart failure drugs effectively help these people, he says.
The pacemaker has three wires or leads: One is threaded into the left ventricle of the heart, one in the right ventricle, and the third is placed in the atrium. In this study, 266 patients were implanted with the devices, but in 132 patients, the devices were not turned on, says Abraham, who is chief of cardiovascular medicine at the University of Kentucky Hospital in Lexington. The study was completed in six months. "At that time, we asked the control group if they wanted their pacemakers turned on and universally, they did," Abraham says.
Sidney Smith, MD, chief science officer for the American Heart Association, tells WebMD that the pacemaker therapy is "very impressive because there really isn't anything else for these people." He says that while pacemaker technology is commonly used to correct irregular heartbeats, "using it for heart failure patients is a new application."
Because the heart beats more efficiently with the resynchronization unit, over time the "heart will remodel. It becomes once again decreased in size," Abraham says. He says that the first patient implanted for this study received the "device in 1998, and he is doing very well two years later."
After six months, half of the patients with active devices could "walk about 50 meters or more -- that's about 150 feet," Abraham says. In the group with inactive devices, only about a third of the patients could walk 50 meters or more. He says that there also was a trend toward lower blood pressure in patients who had activated devices.
Abraham says the device, which is made by Medtronic, will "probably cost about $10,000 to $12,000." The company has a premarket approval for the pacemaker from the FDA.