At least 2.2 million people in the US could be suffering from atrial fibrillation, it is estimated. And the number of patients is forecast to soar.
It is a condition in which part of the heart does not beat the way it should. Instead of beating in a regular, normal pattern, part of the heart beats irregularly and too fast.
The two small upper chambers of the heart, the atria, quiver instead of beating effectively. Although atrial fibrillation is not in itself considered life-threatening, people with it are at an increased risk for blood clots and stroke.
While some experience no symptoms and most others seem to suffer little more than weakness or shortness of breath, atrial fibrillation is now recognized as a major source of strokes and a precursor to potentially fatal deterioration of the heart.
And the best hope for a cure is catheter-based ablation, despite some skeptical voices, commentators say.
The procedure involves burning, freezing, or otherwise neutralizing the portions of the heart muscle where abnormal electrical pulses set off the irregular heartbeats. The technique aims to restore the ability of the two atria, situated at the top of the heart, to effectively gather blood and prime the ventricles, the heart's main pumps.
The original form of atrial ablation, using surgical tools, is still employed, but almost always restricted to cases where the chest is already being cut open for heart valve replacement or other surgery.
But most atrial ablations are now minimally invasive procedures using tiny devices mounted at the end of long, flexible plastic catheters that are threaded into the heart through veins.
Full-scale clinical trials have not yet demonstrated the long-term benefits from the catheter-based treatment. But, based on promising results from less rigorous studies, major medical societies have endorsed it.
Atrial ablation already makes up 30 percent or more of the business of some specialist groups in competitive cardiac care markets like Florida, according to John O. Goodman, a consultant to cardiovascular medical groups.
Advocates of the procedure say it is less invasive than open-heart surgery — the only proven method for curing many patients — and in the long run more cost-effective than drugs, which generally offer temporary relief. Thousands of patients worldwide are estimated to have had the procedure done since 2000.
Besides unlike drugs, which at best help patients manage the symptoms of atrial fibrillation and reduce the risks, ablation saves money in the long run by curing the condition. Drug regimes, which vary widely, can be kept to under $1,000 annually for many patients by prescribing generic drugs, but ablation advocates say the true cost of relying on drugs includes more frequent hospitalizations, lifestyle restrictions for patients on blood thinners and poorer outcomes.
They also note the drugs that are used as the first type of treatment are prescribed "off label" because, in the absence of adequate clinical tests, they have not gained approval for atrial fibrillation. Developed for other heart problems, they include anti-arrythmia agents like amiodarone and generic sotalol, along with anti-clotting drugs, like warfarin. But doctors and patients alike have been dismayed by the side effects of the drugs and their limited long-term effectiveness in controlling atrial fibrillation.
Amiodarone can damage lungs and the liver, cause Parkinson's-like muscle tremors, and contribute to heart failure.
Warfarin, often prescribed as Coumadin, raises the risk of excessive bleeding in any case of injury.
At the same time every major ablation center can cite remarkable success stories. The future belongs to catheter-based ablation, it is asserted.
On the other hand, some regulators and many doctors contend that ablation "cure" rates, while promising, may have been exaggerated by shortcomings in the designs of the clinical trials that supplied the data.
And they say many patients do not fully understand the likelihood — at least 30 percent according to many studies — that they will need subsequent ablations. Patients may also have to continue taking some or all of their drugs or, in some cases, need to have a pacemaker implanted. Moreover, about 2 percent of patients suffer strokes or other serious complications during procedures.
Federal regulators have not approved as safe and effective any of the devices used. So hospitals and doctors are finding it difficult to be fully reimbursed for the procedure's cost, which is generally calculated at $25,000 to $50,000.
"This is one of those areas where the practice of medicine has moved faster than the approval process," said Daniel G. Schultz, head of the Center for Devices and Radiological Health at the Food and Drug Administration.
Dr. Schultz said the F.D.A. would soon schedule a public meeting with medical and industry experts to discuss what is known — and still needs to be known — about the welter of drugs and devices now being used without approval to treat atrial fibrillation.