FIRE and ICE: Cryoablation Matches RF Ablation in Paroxysmal Atrial Fibrillation

Patrice Wendling

April 04, 2016

CHICAGO, IL — Cryoballoon ablation efficacy and safety was on par with radiofrequency catheter (RFC) ablation for the treatment of paroxysmal atrial fibrillation (PAF), results of the FIRE and ICE trial show[1].

"I think they are great results from a practical point of view, from a physician's point of view and, in particular, from the patient's point of view because it will allow more patients to get access to catheter ablation; that's what we really need," lead author Dr Karl-Heinz Kuck (Asklepios Klinik St Georg, Hamburg, Germany) said at the American College of Cardiology (ACC) 2016 Scientific Sessions. The study was  simultaneously published online in the New England Journal of Medicine.

Only about 4% of drug-refractory symptomatic PAF patients, who account for about 30% of AF patients, are treated annually. This is mainly because of the complexity of RFC ablation, whereas cryoballoon ablation is a very simple and easy device to use, he said.

Kuck is working on the third update to the Heart Rhythm Society consensus statement and said he fully expects the trial to become a part of the new guidelines.

Dr C Michael Valentine (Stroobants Cardiovascular Center/Centra, Lynchburg, VA) told heartwire from Medscape that while the trial was relatively small, "it could affect guidelines, and cryoablation would be no different in terms of how they're viewed in the guidelines."

Dr Alfred Bove (Temple University Health, Philadelphia, PA) said in an interview, "If you could show that something had a pretty significant benefit in keeping patients in sinus rhythm postsurgery, I think it would be helpful. That would definitely get in the guidelines, but I don't think we have enough data from this study to make that conclusion."

Recurrent atrial arrhythmia occurred in 80 patients with cryoballoon ablation and 87 with RFC.

Burn or Freeze

Dr Karl-Heinz Kuck

The group randomized 762 of these paroxysmal AF patients in eight European countries to pulmonary-vein isolation by cryoballoon (Arctic Front catheter) ablation with phrenic nerve pacing or radiofrequency (ThermoCool catheter) ablation with 3D electroanatomical mapping.

About 40% of patients were women, well beyond the typical 20% enrollment for ablation trials, which makes the results generalizable across sexes, Kuck said.

The primary efficacy end point of time to first recurrence of AF >30 s, atrial flutter, or atrial tachycardia, use of antiarrhythmic drugs, or reablation occurred in 34.6% of the cryoablation group and 35.9% of RFC patients. The results met the noninferiority threshold (hazard ratio [HR] 0.96; P<0.001), but superiority was not achieved by either group (P=0.74).

Cryoballoon ablation was faster by 20 minutes and had shorter left atrial dwell times, but used 5 more minutes of fluoroscopy time than RFC ablation (21.7 min vs 16.6 min; P<0.001).

Valentine said in a press briefing that the trial confirms what most practitioners feel about the equal efficacy of cryoablation, but he expressed surprise that the procedure time wasn't much faster.

Kuck said procedure times were rather short for both interventions, reflecting the experience of the practitioners, but going forward, cryoablation times could be at least 30 minutes shorter because now they're using a single application to the pulmonary vein rather than applying two bonus applications, as was done in the trial.

There was no difference in the primary end point with the two generations of catheters used in each arm. Use of the newer contact-forced radiofrequency catheters, which has shown improved long-term pulmonary-vein isolation, was limited to only 100 patients, but testing suggested no difference with respect to safety or efficacy, said Kuck.

"Right now there is no recommendation that anyone can make that one catheter is better than another, but I personally believe if we could do the right trials that probably contact force would be better than no contact force," he added.

Safety and Complications

The primary safety end point of time to first all-cause death, all-cause stroke/transient ischemic attack (TIA), or treatment-related serious adverse events occurred was not significantly different between groups (HR 0.78; P=0.24).

Two deaths occurred in the study, both in the cryoballoon arm, but neither were treatment- or cardiac-related, Kuck said.

Groin-site complication was more common with RFC, while phrenic-nerve injury was more common with cryoballoon ablation, occurring at a rate of 2.7%.

Kuck said he hoped the results will help move electrophysiology from niche centers into broader adoption and at some point be used to treat patients at an earlier stage in the disease.

"My dream is, like we did with [Wolff-Parkinson-White] WPW syndrome, the first AF episode: take the patient to the lab, but you need a tool that is safe and simple and can be handled by the average doctor, not the highly specialized doctor," he said.

Panelist Anthony DeMaria (University of California, San Diego) said, "That would be great, but I wonder with a 40% event rate whether we should be rushing into this with the first event."

With just 1-year data, long-term durability is an issue, Kuck acknowledged, but observed that neither technology has been able to achieve 100% long-term pulmonary-vein isolation.

Medtronic funded the trial. Kuck reports consultant fees/honoraria from Biosense Webster, Edwards Lifesciences, and St Jude, and serving as a speaker for Medtronic. Disclosures for the coauthors are listed on the journal website. Valentine reports no financial disclosures. DeMaria reports consultant fees/honoraria from Bracco and Capricor and serving as an officer or having a fiduciary role with Sotera. Bove reported consultant fees/honoraria from Elsevier, Insight Telehealth, and the Merck Manual and ownership interest/partnership/principal role in Insight.

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