Cryoballoon ablation was found to be noninferior to radiofrequency ablation with respect to efficacy for the treatment of patients with drug-refractory paroxysmal atrial fibrillation, and there is no significant difference between the two procedures in regard to patient safety, according to late-breaking clinical trial research presented as part of ACC.16 in Chicago and simultaneously published in The New England Journal of Medicine.

The FIRE AND ICE trial, conducted by Karl-Heinz Kuck, MD, FACC, et al, is the largest randomized trial of its kind, and included participants from 16 centers in eight European countries. "The FIRE AND ICE trial demonstrated that the cryoballoon, a newer, easier-to-use ablation catheter, worked as well as the established technology, which ultimately means that more patients can be treated for atrial fibrillation without having [to go to a] specialized cardiac center," said Kuck. "In addition, there was, in general, a low risk of procedural complications in both groups, demonstrating that catheter ablation has become much safer over the years."

The authors wanted to compare the effectiveness of point-by-point mode applied radiofrequency ablation to that of cryoballoon ablation applied in a single step mode, a newer and less complex technique. The primary efficacy endpoint of the trial was time to first documented recurrence of AF/atrial tachycardia/atrial flutter, prescription of antiarrhythmic drugs or repeat ablation.

The multicenter, randomized, noninferior open-label trial analyzed data gathered from patients ranging from 18 to 75 years old, with symptomatic paroxysmal AF and prior antiarrhythmic drug failure. After exclusions for previous left atrial (LA) ablation, percutaneous coronary intervention or myocardial infarction within three months of enrollment, and other clinical issues, 693 patients undergoing pulmonary vein isolation were randomly assigned in a 1:1 ratio; 352 underwent radiofrequency ablation and 341 underwent cryoballoon ablation.

In-office visits were scheduled at three, six, and 12 months and every six months after. The primary efficacy endpoint occurred in 138 patients in the cryoballoon group and in 143 patients in the radiofrequency group. A pre-specified superiority test performed for the primary efficacy endpoint did not indicate a significant difference between the treatment groups. The most common treatment-related serious adverse events were groin site complication and atrial flutter or atrial tachycardia.

The authors did see significant procedural differences between the two groups. Radiofrequency ablation required less fluoroscopy time (17 vs. 22 minutes). Procedure time was shorter in the cryoballoon group, (124 minutes vs. 141 minutes). LA dwell time in the cryoballoon group was shorter as well (92 vs. 109 minutes). A favorable safety profile was observed in both groups.

"The procedure time was interesting because there are more cost pressures on the health care system for more efficient tools that keep procedures short and predictable," Kuck said.

According to Kuck, the findings could help inform future medical guidelines on the use of different catheter ablation techniques for treating atrial fibrillation. One limitation of the study is that it did not investigate ablation for treating patients with more advanced stages of atrial fibrillation. A separate trial would be needed to assess the ablation techniques'effectiveness and safety for that patient population, he said.

Keywords: ACC Annual Scientific Session, Atrial Fibrillation, Catheter Ablation, Electrocardiography, Heart Conduction System, Outcome Assessment, Health Care, Pulmonary Veins, Quality of Life, Stroke

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