People with congestive heart failure are often given pacemakers to help their hearts pump more efficiently. But doctors have been puzzled by about 40 percent of people given those devices who don't get any better.
They often wind up in the hospital, or they die. Now researchers say they've got the problem figured out. It was a matter of giving the devices to patients whose hearts just weren't that out of sync to begin with.
About 200,000 people with congestive heart failure had the devices implanted from 2006 through 2009. The goal was to correct an abnormal heart rhythm that affects many people with heart failure, making the heart's two powerful pumping chambers, or ventricles, contract out of sync. That reduces the amount of blood pumped.
And since people with congestive heart failure already have weak heart muscle, that inefficient pumping can be a big problem.
After a while, though, it became clear to cardiologists that many people were not being helped by the implants. But studies weren't able to nail the problem. "We wanted to look at data from the clinical trials more carefully," Ilke Sipahi, a cardiologist at the University Hospitals Case Medical Center in Cleveland, tells Shots. So he and his colleagues crunched numbers from five clinical trials involving 5,813 patients.
They found that people whose heart rhythms were off by more than 150 milliseconds benefited from a pacemaker, while people with a variation of less than 150 milliseconds got none. Their findings were published online today in the Archives of Internal Medicine.
Simple, right? Well, the problem is that current guidelines from organizations like the American Heart Association also recommend pacemakers for people with variations of 120 to 150 milliseconds. "They don't benefit at all," says Sipahi.
Not only do they not benefit, but pacemakers are expensive. They're inserted with surgery, bringing with it risk of infection. And the special three-lead pacemakers used on heart failure patients are tricky to install. Sipahi doesn't think that's an issue in why they don't work for many. Instead, he says, it's a clear question of finding out when the devices work, and then applying that lesson to the daily practice of medicine.