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Paroxysmal AF ablation faster, more successful with cryoballoon
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SAN FRANCISCO — Catheter ablation of paroxysmal atrial fibrillation was faster and more successful with a cryoballoon compared with radiofrequency ablation, according to findings from a single-center study presented at the Heart Rhythm Society Annual Scientific Sessions.
A combined approach had a higher success rate than either, but was not superior to the cryoballoon alone, and took much longer to perform than either alone, Ross J. Hunter, PhD, MRCP, said during a presentation.
“[The cryoballoon] is a very appealing option for paroxysmal [AF],” Hunter said. “We need multicenter trials to confirm whether [the cryoballoon] is in fact superior to point-by-point ablation, which is the standard of care at the moment for ablation in paroxysmal AF.”
Hunter, of St. Bartholomew's Hospital, Barts Health NHS Trust and Queen Mary University of London, and colleagues randomized 237 patients with paroxysmal AF undergoing ablation for the first time to radiofrequency ablation, cryoballoon ablation (Arctic Front, Medtronic) or a combined approach. The procedural endpoint was pulmonary vein electrical isolation confirmed using a circular mapping catheter.
The primary endpoint was 1-year success rate, defined as freedom from arrhythmia at 1 year following a 3-month blanking period off antiarrhythmic drugs after a single procedure.
The 1-year success rates were 47% in the radiofrequency group, 67% in the cryoballoon group, and 76% in the combined group (radiofrequency vs. cryoballoon, P=.015; radiofrequency vs. combined, P<.001; cryoballoon vs. combined, P=.166), Hunter said.
Mean procedure times were 211 minutes (interquartile range, 174-256) for the radiofrequency group, 167 minutes (interquartile range, 136-202) for the cryoballoon group and 278 minutes (interquartile range, 243-327) for the combined group (P<.001 for all comparisons).
He noted that in the cryoballoon group, 69% of patients had all pulmonary veins isolated with the cryoballoon alone, and the others required point-by-point ablation to achieve pulmonary vein isolation.
There were four complications in the radiofrequency group, four in the cryoballoon group and three in the combined group, he said, noting that complications in the cryoballoon group were comprised entirely of phrenic nerve palsy, all of which resolved during follow-up. “This is consistent with previous registry data suggesting that complications with cryoballoon, other than resolving phrenic nerve palsy, are actually fairly low, and possibly lower than with radiofrequency ablation,” Hunter said. – by Erik Swain
For more information:
Hunter RJ. Abstract LB02-06. Presented at: Heart Rhythm Society Annual Scientific Sessions; May 7-10, 2014; San Francisco.
Disclosure: Hunter reports no relevant financial disclosures.
Perspective
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Jagmeet Singh, MD, PhD
This is a prospective randomized study examining the efficacy of different ablative approaches for paroxysmal AF. Besides a head-to-head comparison between radiofrequency and cryoballoon ablation techniques, the investigators also examined the combined efficacy of wide encirclement of the pulmonary veins with two additional empirical cryoballoon applications to each of the veins. Cryoballoon ablation seems to have done quite well in this study, with a higher degree of freedom from AF at the 1-year follow-up mark (67% vs. 47% in the radiofrequency group), and 76% in the combined arm. Notably, the duration of the procedure for the cryoballoon ablation arm was shorter than radiofrequency, and was understandably longer in the combined arm. Although the combined strategy had the best results, this was not statistically significant when compared to the cryoballoon ablation arm. However, one could argue that the study may not have been adequately powered to delineate the additional incremental effect of a combined ablation.
Clearly, cryoballoon ablation seems to have come of age and is an accepted first-line ablative strategy for paroxysmal AF. Since the time of this study, there have been advancements in both technologies. The radiofrequency technology has progressed to include contact force sensing and the cryoballoon catheter has evolved into Arctic Front Advance system. Both technologies in their own right provide better and more effective lesion sets compared to their prior versions. It will be interesting to see how these two strategies compare with each other. This will hopefully be addressed by the Fire and Ice study, in which 572 patients are being randomized to radiofrequency vs. cryoballoon ablation with the use of the latest technology for both of these energy sources.
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