A new technique that uses pulses of energy to destroy malfunctioning heart cells can cure both episodic and chronic irregular heartbeats known as atrial fibrillation, Italian researchers report in today's Circulation: Journal of the American Heart Association.
The procedure, called circumferential radiofrequency ablation, uses a catheter tip inserted through the patient's veins and does not require opening the chest to treat the potentially fatal abnormal heartbeats. Pulses of radiofrequency energy are delivered through the catheter to destroy (ablate) the malfunctioning heart cells.
"Our study is the first one to demonstrate that this procedure is suitable not only for episodic but also for permanent atrial fibrillation," says lead author Carlo Pappone, M.D., Ph.D. "This means that even patients with chronic atrial fibrillation may regain normal rhythm."
Atrial fibrillation results from the misfiring of tiny clusters of cells in the atria, the heart's two upper pumping chambers. This out-of-sequence firing results in a disruption of the heart's normal electrical activity, which causes it to beat irregularly.
The condition increases a person's risk of a heart attack or stroke. About 5 percent of people age 65 or older have atrial fibrillation, and the risk of developing it increases with age. The condition affects not only people with coronary heart disease, but also some individuals with high blood pressure and a heart problem called mitral valve disease.
The disorder is usually treated with drugs, but in most cases, medications do not completely eliminate the irregular beats. For several decades, only surgery could cure the disorder. More recently, a less invasive technique called transcatheter linear radiofrequency ablation has been used. However a number of questions remain about this procedure, including the optimal number and location of sites for tissue destruction.
"Our study was undertaken to look for a new solution to treating atrial fibrillation," says Pappone, chief of cardiology and director of the arrrhythmology division at the San Raffaele University Hospital in Milan. "We wanted to find a technique that was efficient and safe enough to warrant its use in a large number of patients."
Last year in Circulation, Pappone and his colleagues reported successfully using another technique, called left atrial linear lesions ablation, to treat individuals with episodic atrial fibrillation.
For the current study, researchers selected 26 patients with fibrillation in the left atrium, which receives blood returning to the heart from the lungs. All participants had abnormal heartbeats that would not respond to treatment with drugs. Fourteen had episodic atrial fibrillation and experienced at least one bout daily of irregular beats that lasted an hour or more. Twelve suffered from chronic atrial fibrillation. Participants ranged in age from 30 to 81 years old, with an average age of 48. Seventeen were men and 9 were women.
The team pushed a tiny catheter into the left atrium and recorded its electrical activity. They determined that the misfiring cells might be located where the pulmonary veins connect to the atrium. Once the trouble sites were located, pulses of radiofrequency energy were delivered to the catheter tip for 60 to 120 seconds. This heated the tip to a maximum temperature of 140°F. Pappone and his colleagues used the catheter to destroy cells in a circular pattern around each pulmonary vein opening, thus blocking some of the lines of electrical conduction that may contribute to atrial fibrillation.
An average of nine months after the procedure, 22 patients (85%) no longer experienced irregular heartbeats. Sixteen of the 22 did not require medications to maintain their normal heart rhythm; the remaining six needed drugs to do so, but were able to use medications that had failed to control their problem prior to the new therapy.
Of the remaining four patients, two with episodic atrial fibrillation improved, but continued to have occasional periods of irregular heartbeats - one or two a month - which would last for less than one hour each time.
Two patients treated for chronic atrial fibrillation had irregular heartbeats that could be treated with drugs. "Although the procedure did not totally eliminate their arrhythmia, it was more responsive to drugs," Pappone says. Moreover, the approximately two hours required to perform the procedure was half the time needed for the earlier ablation technique.
None of the patients suffered intolerable pain, a stroke, or serious blood clotting problems from the procedure, he says. Two patients experienced a mild build up of fluids in the pericardial space, a double sac that surrounds the heart muscle, which is an occasional side effect of catheterization.
During the first 48 hours after the procedure, three patients developed episodes of atrial fibrillation that lasted 7 minutes to 2 hours and ended spontaneously. There were no significant differences in the success rates or complications experienced by patients with episodic versus chronic atrial fibrillation.
Co-authors are Salvatore Rosanio, M.D., Ph.D.; Giuseppe Oreto, M.D.; Monica Tocchi, M.D.; Filippo Gugliotta, B.S.; Gabriele Vicedomini, M.D.; Adriano Salvati, M.D.; Cosimo Dicandria, M.D.; Patrizio Mazzone, M.D.; Vincenzo Santinelli, M.D.; Simone Gulletta, M.D.; and Sergio Chierchia, M.D.