The effect of treating dormant pulmonary vein conduction on the outcome of cryoballoon ablation

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Introduction: Pulmonary vein isolation (PVI) is an important treatment modality for atrial fibrillation (AF). Repeated procedures are often necessary due to electrical reconnection of the pulmonary veins (PVs). Dormant conduction (DC) can be revealed after radiofrequency ablation by infusion of adenosine. This study evaluated the incidence of DC after cryoballoon ablation and the effect of performing additional ablation. Methods: Patients with paroxysmal or persistent AF scheduled for a first ablation procedure were included. PVI was performed with a 23 or 28 mm cryoballoon catheter (Arctic Front, Medtronic, Minneapolis, USA), depending on PV size. At least two 5-minute applications were performed for each vein. Thirty minutes after PVI, a 12-24 mg bolus adenosine was injected to establish DC for each vein. In case of DC, additional applications with cryoenergy were performed until DC was absent. A control group that underwent cryoballoon ablation without adenosine infusion was selected. The number of applications and time-to-isolation of the PV and minimum temperature were registered. Efficacy of ablation was established after 3, 6 and 12 months follow-up with ECG and 24-hour Holter recordings. Results: Thirty-four patients were included for cryoablation with adenosine and 62 patients treated with cryoablation without adenosine. Baseline characteristics were comparable between both groups. During the procedure, DC was found in 38% of patients (13/34) and 11% of the PVs (15/135). After a mean follow-up of 11±2 months, a reduced number of patients (18%) had AF-recurrence after ablation with DC testing, compared to 40% after cryoablation only (p=0.02). Both ablation with adenosine (OR=0.26, 95% CI 0.09-0.74) and paroxysmal instead of persistent AF (OR=0.25, 95% CI 0.07-0.93) were found to independently reduce the risk of AF-recurrence at follow-up with univariate and multivariate analysis (p=0.01 and p=0.04 respectively). Univariate analysis showed three predictors of DC: time-to-isolation of the PV (p<0.01), PV isolation during the first freeze (p<0.01) and minimum temperature (p=0.058). After multivariate analysis, only PV isolation during the first freeze was found to independently reduce the risk of DC (OR=0.06, p<0.01). Conclusion: Detection and treatment of dormant PV conduction with adenosine and additional ablation during cryoballoon ablation improves outcome in patients with AF. Absence of PV isolation during the first freeze was associated with an increased risk of dormant conduction.

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