Cryoballoon Catheters for Atrial Fibrillation Ablation
Abstract & Commentary
By John P. DiMarco, MD, PhD, Professor of Medicine, Division of Cardiology, University of Virginia, Charlottesville Dr. DiMarco is a consultant for Novartis, and does research for Medtronic and Guidant.
Source: Klein G, et al. Efficacy of pulmonary vein isolation by cryoballoon ablation in patients with paroxysmal atrial fibrillation. Heart Rhythm. 2008;5:802-806.
A number of new tools for ablation in patients with atrial fibrillation are now in late-stage clinical trials. In this report, Klein et al from Hanover, Germany, report success using a new cryoablation balloon approach in patients with paroxysmal atrial fibrillation. Patients were selected for inclusion if they had significant structural heart disease or left atrial enlargement. Each had highly symptomatic paroxysmal atrial fibrillation. Pulmonary vein isolation was performed using a new double lumen cryo-balloon (Arctic Front; CryoCath) that was either 23 or 28 mm in size. Transseptal puncture was obtained using standard approach, and a 14-Fr FlexCath™ sheath was advanced into the left atrium over a wire. Pulmonary vein angiography was then performed, and either a 23 or a 28 mm cryoballoon was selected according to the angiographic results. The cryoballoon was positioned in the pulmonary vein antrum, and pulmonary vein angiography was used to verify vessel occlusion. Cryoablation was then applied for five minutes, at least two times in each vein. The left superior, left inferior, right superior and, finally, right inferior pulmonary veins were ablated in sequence. Pulmonary vein isolation was confirmed after the ablation lesions had been performed using coronary sinus pacing and a decapolar mapping catheter placed in the pulmonary vein. If complete electrical isolation was not achieved with the initial lesions, additional lesions could be placed with the same or a smaller size balloon or a conventional cryocatheter.
After the procedure, patients were maintained on anticoagulation for at least three months. They were also continued on antiarrhythmic medications during that time period. Both antiarrhythmics and oral anticoagulants were stopped after three months if the patients were free of symptomatic atrial fibrillation and had only sinus rhythm on serial ambulatory electrocardiograms.
The study group included 10 men and 11 women with a mean age of 56 ± 6 years. Fourteen patients had a history of hypertension and three had a history of coronary artery disease. The mean procedure duration was 165 ± 35 minutes, with 39 ± 9 minutes of fluoroscopy time required. A single balloon technique successfully isolated 81 of 85 treated pulmonary veins. Two patients required use of a second balloon, and one patient required a standard cryocatheter to achieve pulmonary vein isolation. One right superior pulmonary vein and one right inferior pulmonary vein were not completely isolated. During a mean follow-up of 172 ± 60 days, three patients had symptomatic atrial fibrillation recurrences. One patient underwent a second cryoballoon ablation procedure and then was free of recurrent AF. There were no deaths, cardiac tamponades, or thromboembolic events associated with the procedure. Three patients developed phrenic nerve palsy. In two patients, the phrenic nerve paralysis completely resolved after six and nine months. One patient still had persistent phrenic nerve paralysis two months after his ablation procedure at the time this paper was written. These phrenic nerve injuries occurred despite pacing the phrenic nerve during the ablation of the right superior vein in each case.
Klein et al conclude that this cryoballoon ablation technique appears to be highly effective in this highly selected group of patients. They encourage future studies with this device.
Commentary
The most common approach for ablation of paroxysmal atrial fibrillation involves isolation of the pulmonary vein using a large number of radiofrequency lesions placed in circumferential fashion in the pulmonary vein antral regions or the left atrium. This technique requires extensive catheter manipulation, and can be quite time consuming. The cryoballoon technique described here appears to be highly effective at isolating the pulmonary veins in a relatively simple procedure. The advantage of this cryoballoon approach is that it yielded highly reproducible pulmonary vein isolation and, at least in the short follow-up in this series, reconnection, a common problem with radiofrequency lesion, was infrequent. It remains to be seen, however, whether this technique will be useful in patients with enlarged left atria or unusual pulmonary vein anatomy. Multiple pulmonary veins or common pulmonary vein ostia are quite common, and it is likely that a significant portion of patients will not be approachable using only the two cryoballoon sizes described here. However, pulmonary vein anatomy can be assessed with a pre-procedure cardiac MR or CT. In patients with favorable anatomy, the cryoballoon ablation approach looks very promising.
The occurrence of phrenic nerve palsy is of concern. Fortunately, it appears that it usually resolves over time. However, even with pacing the phrenic nerve during the procedure, the complication still occurred in three of the 21 patients. Better methods to avoid this will need to be developed if the cryoballoon is to become widely accepted as a first choice technique.
A number of new tools for ablation in patients with atrial fibrillation are now in late-stage clinical trials.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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