Cryoenergy Or Radiofrequency for Pulmonary Vein Isolation (COR)

This is a prospective single-center randomized trial comparing the efficacy and safety of PV cryoablation with the Arctic Front® catheter versus the standard PV isolation using radiofrequency irrigated tip catheters. The efficacy of both strategies will be evaluated from a clinical point of view and from the detection and quantification of AF episodes by means of the Reveal XT® implantable loop recorder.

Pulmonary vein (PV) isolation using a radiofrequency catheter is the most widespread technique for atrial fibrillation (AF) ablation. These procedures are difficult and time-consuming, because they require precise catheter manipulation and multiple radiofrequency applications. Thus, alternative techniques are being investigated to simplify the procedure. Recently, a cryoenergy balloon catheter has been developed for PV isolation (Arctic Front®, Cryocath Technologies). When this catheter is deployed at the PV antrum, it can create a circumferential lesion around the PV ostium by delivering a single cryoenergy application. An implantable loop recorder for AF detection has been made available (Reveal XT®, Medtronic). It may help taking clinical decisions regarding anticoagulant and antiarrhythmic therapy and, at the same time, it may be a powerful tool to evaluate the efficacy of different therapeutic strategies. This is a prospective single-center randomized trial comparing the efficacy and safety of PV cryoablation with the Arctic Front® catheter vs. the standard PV isolation using radiofrequency irrigated tip catheters. The efficacy of both strategies will be evaluated from a clinical point of view and from the detection and quantification of AF episodes by means of the Reveal XT® implantable loop recorder.

A deflectable over-the-wire cryoablation balloon catheter (Arctic Front®) will be inflated and be positioned at each PV antrum. Then, cryoenergy will be delivered for 300 seconds. During cryoablation of the right PVs, the right phrenic nerve integrity will be monitored by the observation of right hemi-diaphragm contractions in response to right phrenic nerve pacing at the superior vena cava. Once the 4 PVs are cryoablated, the Arctic Front® catheter will be replaced by a decapolar PV mapping circular catheter (Lasso®, Biosense Webster, Diamond Bar, California, EEUU) to evaluate PV conduction. A second cryoablation application may be delivered at each PV, if necessary. Crossover to RF ablation to complete PV isolation is discouraged.

Ablation approach is ostial electrical isolation of all PVs with simultaneous use of the CARTO® electroanatomic mapping system (Biosense Webster, Tirat-Ha-Carmel, Israel). PV isolation will be performed by delivering RF energy at ostial sites with earliest PV potentials. Flow rate during the RF applications will be set at 15 mL/min (baseline 2 mL/min). Temperature and power limits will be set at 45ºC and 35 W. It will be allowed a 5 W reduction in power limit setting for small PVs (angiographic supero-inferior diameter > 12 mm), and a 5 W increase in areas located away from the esophagus, and for focal applications at sites resistant to ablation or recurrent gaps. The end-point of ablation will be to achieve bidirectional PV conduction block.

Within the first 12 months from ablation (using a blanking period of 3 months following ablation, and without the use of any blanking period)

Proportion of patients with episodes of regular atrial tachycardia or atrial flutter requiring treatment with drugs, electrical cardioversion or ablation.

Procedure time (minutes elapsed from the first puncture of the femoral vein to the removal of the last catheter)

Ablation time (minutes elapsed from the onset of the first energy delivery to the end of the last energy delivery).

Inclusion Criteria: Symptomatic recurrent paroxysmal AF (>2 episodes in the last 6 months), and Refractory to one or more class I or III antiarrhythmic drugs, and PV anatomy consisting of 4 single PV, with the long diameter of the right superior PV ostium ≤ 20 mm. Exclusion Criteria: Age: < 18 or > 75 year-old Prior AF ablation Pregnancy Concomitant acute illness Hyperthyroidism Moderate to severe valvular heart disease Prior cardiac surgery Left atrium > 50 mm (anteroposterior diameter, parasternal long-axis view) Intracardiac thrombus Contraindications for anticoagulant therapy Inability to be followed in our center for at least 1 year