Burning Heart Tissue Beats Atrial Fibrillation
TUESDAY Jan. 26, 2010 -- When drug therapy can't control the dangerous heart rhythm disorder called atrial fibrillation, burning out the cardiac tissue responsible for the abnormality will do the job in most cases, a new study has found.
Called catheter ablation, the burning technique ended episodes of abnormal heartbeat and improved the quality of life over a nine-month period for two-thirds of the people in the study who had the procedure, compared with 16 percent of those who were started on a new drug regimen.
The finding was reported in the Jan. 27 issue of the Journal of the American Medical Association.
In atrial fibrillation, the upper chambers of the heart have episodes in which they quiver rather than beat to circulate blood. The episodes are often uncomfortable, causing chest tightness, pain and other symptoms. In addition, clots can form in the stagnant blood, traveling to block arteries and causing heart attacks or strokes. An estimated 2 million Americans have the condition, which becomes more common with aging.
A variety of drugs are used to treat atrial fibrillation, but initial drug therapy will not satisfy about half the people with the condition, said study author Dr. David J. Wilber, who is director of the Cardiovascular Institute at Loyola University Medical Center in Illinois.
"What has become clear is that once you fail one drug, your chances of responding to another drug are limited," he said. At that point, Wilber said, he might suggest catheter ablation, in which an electrical impulse is transmitted to eliminate the source of the irregular heartbeat.
The study, done at 19 hospitals in the United States and abroad, included 167 people whose atrial fibrillation was not controlled by one or more drugs. Of that group, 106 people had catheter ablation treatment and 61 were given a different drug. The trial was cut short because of the obvious advantages of catheter ablation, the researchers reported.
But that does not mean that catheter ablation is the first choice for treatment of atrial fibrillation, Wilber noted. He said he suggests it only when drug therapy clearly is not working, with the choice largely left up to the person with the condition.
"Some patients may say they want to try anything else first, some say they want the invasive procedure [catheter ablation]," he said. "This study offers the possibility of catheter ablation replacing drug therapy in these cases because the trial shows those patients do better."
Catheter ablation does have its risks, Wilber acknowledged. Previous studies have found a complication rate of 1 percent to 5 percent, he said. No such complications were seen in the new study.
"The amount of heart tissue that is destroyed has a relatively small effect on heart function," Wilber said. "That tissue isn't missed by the heart as much as you might expect."
And though many large medical centers are equipped for catheter ablation, expertise in the technique can differ, he said. "There is a very large range of experience," Wilber said. People considering the procedure should check published reports of clinical trials for evidence of a given medical center's expertise.
"I don't think there is a simple way right now" to do this, Wilber said, adding that "there is considerable interest in a national registry, as for heart surgery."
Dr. Frank Marchlinski, director of the electrophysiology program at the University of Pennsylvania and a member of the research team, said the study "demonstrates convincingly that, with catheter ablation, the outcome is dramatically better."
Like Wilber, Marchlinski said he, too, would suggest the procedure when drug therapy isn't working.
"I give patients that information, describe the opportunity of catheter ablation and the risk of catheter ablation," Marchlinski said. "I tell them that there is only a 20 percent chance of long-term success with other drugs."
But because atrial fibrillation generally is not immediately life-threatening, "it doesn't mean with absolute certainty it has to be done," he said. "This is an elective procedure. It is appropriate to consider it for those who do not want to take drugs."
The U.S. National Heart, Lung, and Blood Institute has more on catheter ablation.
Posted: January 2010