Study Shows Positive Results with Both Cryoballoon, RF Ablation for A-fib
In patients with atrial fibrillation (A-fib), cryoballoon treatment offers long-term outcomes that rival those of radiofrequency ablation. The findings were published online November 28, 2012, ahead of print in the Journal of the American College of Cardiology.
Jürgen Vogt, MD, and colleagues at Ruhr University Bochum (Bad Oeynhausen, Germany), prospectively enrolled 605 consecutive patients slated for cryoballoon pulmonary vein isolation from July 2005 to August 2011. Most (n = 579) had symptomatic paroxysmal A-fib; the remainder (n = 26) developed persistent A-fib between the time of scheduling and the actual cryoballoon ablation procedure.
Both Treatments Offer Long-term Protection
Pulmonary vein isolation was successfully achieved via cryoballoon alone in 551 patients (91.1%) without need for touch-up. Among them, 26.7% were treated using a 23-mm balloon, 25.6% with a 28-mm balloon, and 47.7% with both balloon sizes.
Procedures lasted a median of 156 minutes (interquartile range [IQR], 131-189 minutes), with a median fluoroscopy time of 25.2 minutes (IQR, 19.6-32.2 minutes). With growing experience between the first 50 and the last 85 cases in the series, procedure times decreased by approximately 100 minutes and fluoroscopy times also were shortened (P < 0.05 for both).
The most common acute adverse event was phrenic nerve palsy, observed in 12 patients (2%; 10 cases with the 23-mm balloon and 2 with the 28-mm balloon) before resolving within 3 to 9 months. Ten cases of hemoptysis with hematoma or edema around pulmonary veins were observed; all healed within 10 days.
After treatment, patients received antiarrhythmic therapy with formerly ineffective drugs for 3 months to facilitate maintenance of sinus rhythm. A total of 46 patients had A-fib recurrences during the 3-month period, half of whom had no further A-fib and did not undergo repeat procedures.
Long-term follow-up over a median of 30 months (IQR, 18-48 months) was available in 451 patients. More than half (61.6%) were free of A-fib recurrence after drug treatment and did not undergo subsequent intervention. Freedom from A-fib after 1, 2, or 3 repeat treatments using cryoballoon or radiofrequency ablation was 74.9%, 76.2%, and 76.9%, respectively; the 2 procedures offered similar success rates. The most rapid decline in outcome was seen between the first year after treatment, with 22.4% of patients having recurrences from 4 to 12 months and 10.6% having recurrences thereafter.
Compared with the 28-mm balloon, freedom from A-fib was significantly higher after treatment with the 23-mm balloon or 2 balloons, one of each size (P = 0.0018 and P < 0.001, respectively).
An Evolving Field
“In our clinical experience, long-term rates of freedom from [A-fib] over several years after cryoballoon ablation appear comparable to those with radiofrequency energy ablation, although randomized, controlled studies would be needed to demonstrate this conclusively,” the investigators write. “Selecting the appropriate balloon size for each individual vein anatomy to ensure the best fit increases long-term success rates, but there is a trade-off in increased procedural risk with the smaller balloon that should be taken into account.”
Dr. Vogt told TCTMD that clinicians in Germany, and in Europe as a whole, are more familiar with cryoballoon ablation than US physicians because the technique has been available there since 2005. The risk of A-fib recurrence has declined with growing experience but this shift has “depended more on the cooling profile of the balloon than the learning curve,” he explained in an e-mail communication.
At the time of the current study, the cooling profile of available balloons was not yet homogenous, and operators often had to work with 2 balloon sizes in individual patients to improve outcomes, Dr. Vogt reported.
With the more recently developed Arctic Front Advance cryoablation catheter (Medtronic, Minneapolis, MN), which his group has used in more than 60 patients, Dr. Vogt predicted that efficacy will improve. “[T]hat means faster, more reliable, and more cost-effective [treatment] with 1 balloon per procedure in 98% of patients,” he noted, adding that adverse side effects could be “minimized to less than 1%” in experienced hands.
The cryoballoon technique, however, “is much more simple and straightforward” than radiofrequency ablation, which has a more difficult learning curve and longer training time, Dr. Vogt commented. He advised that cryoballoon procedures should be performed by electrophysiologists, because interventional cardiologists “are not familiar with the [pulmonary vein] potentials and differential diagnosis of rhythms [that arise] during A-fib ablations.”
Dr. Vogt highlighted 2 ongoing studies in Germany—the Fire and Ice randomized trial and the FREEZE cohort study—that are comparing the Artic Front Advance cryoballoon vs. radiofrequency ablation.
Techniques and device technology changed over the course of the study. The left atrium was accessed by double transseptal puncture in the first 253 patients and by a single transseptal puncture using the FlexCath sheath (Medtronic) in later patients. The LASSO catheter (Biosense Webster; Diamond Bar, CA) was utilized for mapping through 2010 when the Achieve mapping catheter (Medtronic) was introduced. In the early cohort, the Freezor MAX focal cryoablation catheter (Medtronic Cryocath, Pointe-Claire, Canada) was used for touch-up; subsequently, patients underwent additional balloon freezes instead.
Vogt J, Heintze J, Gutleben KJ, et al. Long-term outcomes after cryoballoon pulmonary vein isolation: Results from a prospective study in 605 patients. J Am Coll Cardiol. 2012;Epub ahead of print.
- The study was supported by an unrestricted grant from Medtronic.
- Dr. Vogt reports receiving speaker and advisory board honoraria from Medtronic.