40. Worldwide experience with the Arctic Front cardiac CryoAblation System for treatment of atrial fibrillation

Abstract

Introduction: Pulmonary vein (PV) isolation by percutaneous catheter ablation is a cornerstone for treatment of atrial fibrillation (AF). The 2012 HRS/EHRA/ECAS Expert Consensus Statement on Catheter and Surgical Ablation of Atrial Fibrillation made a Class 1 recommendation for catheter ablation for symptomatic paroxysmal AF refractory or intolerant to at least one Class 1 or 3 antiarrhythmic medication. The Arctic Front Cardiac CryoAblation System, a minimally invasive device that enables intravascular deployment of a cryoballoon to the left atrium, creates circumferentially transmural lesions at the PV antrum, blocking ectopic conduction to the LA from PV triggers that initiate AF. The device has been used to treat over 37,000 cases worldwide. A recent randomized, controlled clinical trial, the Sustained Treatment of Paroxysmal Atrial Fibrillation study (STOP AF), evaluated safety and efficacy of cryoablation (CRYO) in comparison with anti-arrhythmic drug therapy (AAD) for drug- refractory recurrent, symptomatic paroxysmal atrial fibrillation. Acute procedural success was achieved in 98.2% (160/163) of patients randomized to cryoablation. At 12 months, 69.9% of CRYO patients demonstrated treatment success compared to 7.3% of AAD patients. The overall rate of serious adverse events in the trial was 12.3% for the CRYO arm in comparison to 14.6 for AAD ( p = 0.69). Methods: To further explore worldwide experience with the device and cryoablation procedure, a literature search was conducted for all data published from June 14, 2005 to November 16, 2012. Only articles that contained both safety and clinical outcomes results for Arctic Front or the next generation Arctic Front Advance System were included. Results: 44 studies reporting on rates of acute PVI and chronic efficacy (3–21 months) from 2722 patients in 15 countries were identified. With the addition of STOP AF ( n = 163 CRYO) and an FDA approved continued access protocol (CAP, n = 78), data from 2963 patients were analyzed. Fourteen of these studies, representing data from 13 countries, reported outcomes on 1293 patients at 12 months or longer. Twelve were nonrandomized, prospective observational studies and one was a randomized trial. In these studies, rates of acute PVI ranged from 100 to 67% while chronic efficacy for paroxysmal AF was 88–59%. The overall complication rate was low (6.1%) among all 44 studies, with 1 stroke, 2 TIA, 6 transient esophageal ulcerations, 3 delayed gastric emptying/gastroparesis and 7 pericardial effusions being the most serious adverse events in 2722 patients. As in the CAP, phrenic nerve palsy was the main complication reported in the literature, with an incidence of 4.66% compared to 11.2% in STOP AF and 3.7% in the CAP. Conclusions: Multiple studies, including data on over 1300 patients with at least one year followup duration, support the effectiveness and safety of the Arctic Front device and appear to be consistent with STOP AF results. Two ongoing, multi-center, nonrandomized postmarket studies sponsored by Medtronic continue to evaluate long term clinical outcomes of drug-refractory paroxysmal AF patients treated with the Arctic Front or the next generation Arctic Front Advance.