New Device Treats Common Heart Rhythm Disorder
SATURDAY March 28, 2009 -- An implanted device may soon replace the anti-clotting drug warfarin as the first line of treatment for many people with atrial fibrillation, a new study suggests.
People with atrial fibrillation have a sixfold increased risk of stroke, the researchers noted, and typically need to take warfarin for the rest of their lives. Atrial fibrillation is a common heart rhythm problem that causes the upper chamber of the heart to beat irregularly.
"One in four people over 50 will develop atrial fibrillation," lead researcher Dr. David R. Holmes Jr., the Scripps Professor of Medicine at the Mayo Graduate School of Medicine, said during a morning teleconference at the American College of Cardiology annual meeting Saturday in Orlando, Fla.
About 3 million people in the United States have atrial fibrillation, and 16 million Americans will have the condition by 2050, Holmes said. Stroke is the most serious complication related to atrial fibrillation, he noted.
"We know that in those patients with atrial fibrillation that the clot that causes that stroke comes from a certain area of the heart called the left atrial appendage," Holmes said, explaining that the appendage is a muscular pouch connected to the left atrium. "The device isolates the left atrial appendage."
To implant the device, an interventional cardiologist uses a catheter inserted in a leg vein to guide the device into the heart; the device travels through the heart's right chamber and is deposited into the left atrium through a puncture hole between the two chambers of the heart, the researchers explained.
Current treatment with warfarin is effective in preventing strokes caused by clots associated with atrial fibrillation, but its use needs to be monitored monthly to assure patients are receiving the safest and most effective dose because it can cause serious bleeding if given in doses that are too high, Holmes noted.
In the Embolic Protection in Patients With Atrial Fibrillation (PROTECT AF) trial, researchers compared treatment with warfarin to a fabric-covered, expandable cage called the WATCHMAN. The device blocks blood clots that typically form in the heart's left atrial appendage. The 707 patients were randomly assigned to one of the two treatments.
"Efficacy was dramatically better with the device, and stopping the warfarin," Holmes said.
The researchers found that patients with the WATCHMAN had a 32 percent lower risk of stroke and cardiovascular death compared with warfarin therapy. This was especially true for hemorrhagic stroke, which causes bleeding in the brain and is usually fatal, Holmes noted.
In addition, there were fewer complications with the device, once it was implanted, compared to warfarin. Most complications with the device occurred when placing it in the heart, but these complications now occur in only 1 percent of patients, Holmes noted.
The researchers concluded that the device is an effective alternative to warfarin for preventing stroke in patients with atrial fibrillation, particularly those at the highest risk of stroke.
"A strategy like this can be used in patients with non-valvular atrial fibrillation to prevent stroke, and get them off warfarin," Holmes said.
Dr. Gregg C. Fonarow, professor of cardiology at the University of California, Los Angeles, thinks this device will benefit many patients with atrial fibrillation.
"The major risk of atrial fibrillation is blood clots forming in the heart, and then breaking loose to cause stroke. Most of these blood clots form in the appendage of the left atrium," Fonarow said.
The only effective treatment until now was lifelong use of warfarin. Researchers have been searching for alternative therapies to warfarin to protect patients with atrial fibrillation from stroke without success for decades, Fonarow noted.
"The findings from this clinical trial are very impressive," Fonarow said. "Although there were some procedure-related complications, treatment with this novel device will be very attractive and provide patients with atrial fibrillation effective, long-term protection from stroke and systemic embolization without the bleeding risks associated with warfarin."
For more information on atrial fibrillation, visit the American Heart Association.
Posted: March 2009