The COR trial: a randomized study with continuous rhythm monitoring to compare the efficacy of cryoenergy and radiofrequency for pulmonary vein isolation.

BACKGROUND: Results from randomized trials designed to compare cryoenergy with radiofrequency for pulmonary vein (PV) isolation are lacking.

OBJECTIVE: To compare the efficacy of a simplified strategy for PV cryoablation (group C) vs PV isolation with open-irrigated radiofrequency catheters (group R).

METHODS: Fifty patients with paroxysmal atrial fibrillation (AF) and 4 independent PVs received a Reveal XT implantable cardiac monitor and were randomized to group C or group R. In group C, PV ablation was done with a single Arctic Front balloon (23 or 28 mm) per patient and two 300-second applications per PV. No further applications were delivered to close residual conduction gaps. In group R, bidirectional PV conduction block was pursued with Lasso and Navistar ThermoCool catheters and the CARTO system. The primary end point was the proportion of patients remaining free from AF recurrences ≥2 minutes without taking antiarrhythmic drugs 12 months after ablation.

RESULTS: The primary end point was met by 12 (48%) patients in group C and 25 (68%) patients in group R (odds ratio 0.43; P = .05). This difference disappeared after adjustment for acute procedural outcome. In patients for whom all 4 PVs were blocked at the end of the procedure, there was no difference between group C and group R in the primary end point (67% vs 68%; P = .94).

CONCLUSIONS: The efficacy of the simplified strategy for PV cryoablation tested in this study is inferior to PV isolation using open-irrigated radiofrequency catheters with electrophysiological and electroanatomical guidance. Complete PV conduction block is critical to the success of AF ablation.