Burning away heart tissue using a procedure called catheter ablation is dramatically more successful than drugs at treating atrial fibrillation, a common heart rhythm disorder, according to a new landmark study published in a leading journal today.
Lead researcher Dr. David Wilber, director of the Cardiovascular Institute at Loyola University Chicago Stritch School of Medicine, and colleagues, write about their findings in the 27 January online issue of JAMA, Journal of the American Medical Association. Wilber presented data from this study to the Heart Rhythm Society’s Scientific Sessions last year.
They found that after one year, two thirds of patients who received catheter ablation to treat an irregular heartbeat caused by atrial fibrillation (A-Fib), no longer experienced recurrent irregular heartbeats or symptoms, compared with only 16 per cent of those treated with drugs.
The researchers reported that the results were so good the trial stopped early. The study was sponsored by Biosense Webster, who provided the catheters.
A-Fib is the most common type of irregular heartbeat. It occurs when electrical signals, which control the muscles of the heart, become erratic and instead of beating regularly, the upper chambers of the heart quiver. This disrupts blood flow, not all the blood gets through the heart properly, and so clots form and can cause strokes and heart failure.
People with A-Fib experience dizziness, chest pain, fatigue, heart palpitations, shortness of breath, fainting and lightheadedness. The condition affects more than 2 million Americans, with about 160,000 new cases found every year. The numbers are rising, partly because the population is getting older and partly because of the obesity epidemic.
Wilber, told the press that A-Fib disables people:
“They have no energy. They can’t work. They have a very poor quality of life,” he said.
In their study, patients who underwent ablation reported major improvements in their quality of life immediately, and this lasted throughout the nine months of follow up. But among the patients who received the drug therapy alternative, there were no significant quality of life improvements, the researchers told the press.
For the study, Wilber and colleagues studied 167 patients with A-Fib who had tried at least one drug but with no success.
The participants were being treated at 19 medical centers, 15 of which were in the US. Their average age was 55 and 33.5 per cent of them were women. They had been having symptoms of A-Fib on average for 5.7 years, and had on average undergone drug treatment for the condition with 1.3 drugs but with no success.
The researchers randomly assigned the patients to receive either ablation (106 patients) or a drug that was different to those they had already tried (61 patients).
The results showed that:
- At the end of the 9 month evaluation period, 66 per cent of the catheter ablation patients remained free from “protocol-defined treatment failure” compared with 16 per cent of those treated with drugs (ADT, antiarrhythmic drug therapy).
- The hazard ratio of catheter ablation to ADT was 0.30 (95 per cent confidence interval, CI, ranged from 0.19 to 0.47, P
The researchers concluded that:
“Among patients with paroxysmal AF [atrial fibrillation] who had not responded to at least 1 antiarrhythmic drug, the use of catheter ablation compared with ADT resulted in a longer time to treatment failure during the 9-month follow-up period.”
One of the patients was 36-year old Robin Drabant from Hanover Park, Illinois. She said the condition made her feel 90 years old. She was taking a maximum dose of an A-Fib drug, which caused her to feel fatigued and gain weight, and she still experienced daily irregular heart rhythm episodes, lasting about 10 seconds or more:
“I would lose my breath and could feel my heart racing and fluttering,” she said.
Wilber performed a catheter ablation on Drabant’s heart in May 2008. Since then she has had no more A-Fib episodes and said “I had great results”.
A-Fib can be treated with various drugs with different effects. For example, beta blockers and calcium-channel blockers can slow the heart rate during an arrhythmic episode: others like flecainide and propafenone, can help keep the rhythm steady.
But even when drugs succeed in stabilizing the heart rhythm, their side effects can be debilitating and significantly impoverish a person’s quality of life. Currrently in the US, when drugs don’t work, patients are offered other treatments including surgery and catheter ablation, a relatively new procedure compared to drugs which have been around 30 or 40 years or so.
During a catheter ablation, an electrophysiologist burns away bits of heart tissue that cause the erratic electrical signals using a thin flexible tube (the catheter) that is inserted through the blood vessels into the heart. The tip of the catheter delivers radiofrequency heat waves that burn away the tissue.
Cather ablation can have side effects, these include irritation of the heart lining, fluid in the lungs or around the heart, bleeding, clots and stroke. But none of these occured in this trial, said the researchers.
Wilber said an experienced center should get the same results as they found on the study. At Loyola they do about 500 ablations a year, making it one of the highest volume centers in Midwest US, according to a recent press statement.
This trial is the largest so far to compare catheter ablation to drugs in the treatment of A-Fib. Another major trial called CABANA that is following 3,000 patients for three years, is currently investigating whether patients receiving ablation live longer than patients treated only with drugs.
“Comparison of Antiarrhythmic Drug Therapy and Radiofrequency Catheter Ablation in Patients With Paroxysmal Atrial Fibrillation: A Randomized Controlled Trial.”
David J. Wilber; Carlo Pappone; Petr Neuzil; Angelo De Paola; Frank Marchlinski; Andrea Natale; Laurent Macle; Emile G. Daoud; Hugh Calkins; Burr Hall; Vivek Reddy; Giuseppe Augello; Matthew R. Reynolds; Chandan Vinekar; Christine Y. Liu; Scott M. Berry; Donald A. Berry; for the ThermoCool AF Trial Investigators.
Source: Strich School of Medicine.
Written by: Catharine Paddock, PhD