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Cryoballoon Ablation for Paroxysmal AF
Study Questions:
What is the long-term efficacy of cryoablation using a second-generation cryoballoon (CB2) in patients with paroxysmal atrial fibrillation (AF)?
Methods:
CB ablation using a second-generation balloon was performed in 344 patients (mean age, 60 years; 66% men; left atrial diameter, 40 mm; CHADS2 score ≤1, 79%; body mass index, 30 kg/m2) with paroxysmal AF at 39 North American centers. Surveillance for phrenic nerve injury was performed by pacing the phrenic nerve (at the superior vena cava) during ablation of the right-sided pulmonary veins (PVs). The number and duration of lesions was at the discretion of the operator, but typically a minimum of two lesions/PV lasting for 180-240 seconds were delivered. Patients were followed for a minimum of 3 years. Data regarding complications, and acute- and long-term success were collected. Arrhythmia surveillance was performed using electrocardiograms, 24- to 48-hour Holter monitoring, or 30-day ambulatory monitoring. Treatment with antiarrhythmic medications was not prespecified.
Results:
Procedural and fluoroscopy times were 232 and 20 minutes, respectively. PV isolation was acutely successful in 1,341 of 1,350 veins (99.3%). Major complications occurred in 20 patients (5.8%), with phrenic nerve injury in 11 (3.2%). Phrenic nerve injury resolved (median time to resolution, 105 days) in all but one patient over a follow-up period of 36 months. Freedom from atrial arrhythmias was achieved in 79% of patients at 12 months, 71% at 24 months, and 64% at 36 months. A repeat procedure was performed in 63 patients (18%). Twelve percent of patients were taking rhythm-controlling medications at 36 months.
Conclusions:
The authors concluded that CB-based PV isolation eliminates atrial arrhythmias in about two-thirds of the patients with paroxysmal AF with a low risk of complications.
Perspective:
In multicenter studies, the efficacy of CB- and radiofrequency-based PV isolation is comparable in patients with paroxysmal AF. The risk profiles of the two modalities differ, with a higher risk of phrenic nerve injury with the former, and a higher risk of perforation with the latter. The late attrition in efficacy seen in this study has also been reported in prior studies utilizing radiofrequency ablation, reinforcing the importance of durable PV isolation, and secondary prevention/risk factor modification.
Keywords: Anti-Arrhythmia Agents, Arrhythmias, Cardiac, Atrial Fibrillation, Body Mass Index, Catheter Ablation, Cryosurgery, Electrocardiography, Electrocardiography, Ambulatory, Fluoroscopy, Phrenic Nerve, Pulmonary Veins, Risk Factors, Secondary Prevention, Vena Cava, Superior
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