Abstract
BackgroundThe optimal dosage for cryoablation of atrial fibrillation (Cryo-AF) is still unknown. To evaluate the efficacy of an individualized freeze duration, we compared the clinical outcome of patients treated with a time-to-pulmonary vein isolation (TT-PVI) or temperature-guided ablation protocol to the outcome of patients treated with a conventional ablation protocol.MethodsA total of 164 consecutive patients were included in the study. One method employed was a conventional dosing protocol (at least 2 applications of 180 s each) (the Cryo-AFConventional group n = 84), and the second method had a shorter protocol that was based on the TT-PVI or achievement of − 40 °C within 60 s (the Cryo-AFDosing group n = 80)ResultsWe treated 656 pulmonary veins (PVs) with 1420 cryotherapy applications. The mean number of applications per patient was 8.7 ± 0.8, with no difference between groups (Cryo-AFConventional, 8.7 ± 0.8 versus Cryo-AFDosing,8.6 ± 0.8; P = 0.359). The Cryo-AFDosing group required significantly less total cryotherapy application time (990.60 ± 137.77versus 1501.58 ± 89.60 s; P < 0.001) and left atrial dwell time (69.91 ± 6.91 versus 86.48 ± 7.03 min; P < 0.001) than the Cryo-AFConventional group. Additionally, the Cryo-AFDosing group required significantly less total procedure time (95.03 ± 6.50 versus 112.43 ± 7.11 min; P < 0.001). We observed acute ATP-induced or spontaneous vein electric reconnections in 13 veins (1.98%) after 20 min. The reconnection rates between the Cryo-AFConventional and Cryo-AFDosing groups were similar in that 2.98 and 0.94% of the initially isolated veins were reconnected, respectively, (P = 0.061). There was no difference in the recurrence rate of free atrial arrhythmia after a 1-year follow-up, which were 78.75% in the Cryo-AFDosing group versus 78.57% in the Cryo-AFConventional group (P = 0.978).ConclusionA novel Cryo-AF dosing protocol guided by temperature or the TT-PVI can be used to individualize an ablation strategy. This new protocol can lead to a significant reduction in duration of the procedure, the cryoenergy dosage and the left atrial dwell time. The procedure had equal safety and similar acute and 1-year follow-up outcomes compared to the conventional approach.
Highlights
The optimal dosage for cryoablation of atrial fibrillation (Cryo-Atrial fibrillation (AF)) is still unknown
Used ablation strategies are often based on a fixed freeze-cycle duration of 180 s that is followed by a bonus freeze cycle of the same length after successful Pulmonary vein isolation (PVI)
This study evaluated the safety and efficacy of a shorter application strategy, based on the time-topulmonary vein isolation (TT-PVI) or achievement at − 40 °C within 60 s (Cryo-AFDosing), compared with the conventional strategy (Cryo-AFConventional)
Summary
The optimal dosage for cryoablation of atrial fibrillation (Cryo-AF) is still unknown. Pulmonary vein (PV) isolation (PVI) is a critical component of AF ablation. The second-generation CB (CB2, Arctic FrontAdvanceTM, Medtronic, Inc.) was released with technical developments that allowed a larger and more consistent zone of freezing on the balloon surface. These developments translated into critical improvements in clinical and procedural outcomes when compared to the previous generation [4, 5]. The ideal cryoablation of atrial fibrillation (Cryo-AF) dose is not well established, and predictors of durable electrical isolation are poorly known. Prior research has suggested the time-to-pulmonary vein isolation (TT-PVI) procedure was a critical variable [7, 9]
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