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Incidence and predictors of dormant conduction after cryoballoon ablation incorporating a 30-min waiting period.

AIMS
Electrical reconnection after pulmonary vein (PV) isolation is associated with atrial fibrillation (AF) recurrence. Reconnection may already develop within a 30 min waiting period and may only occur as dormant conduction (DC) revealed by adenosine infusion. This study determines incidence and predictors of DC after cryoballoon ablation incorporating a 30 min waiting period and the effect of treating this 'late' DC on 1 year AF-recurrence.


METHODS AND RESULTS
Consecutive patients scheduled for a first ablation were prospectively included. Intravenous adenosine was administered 30 min after PV isolation to unmask DC (adenosine+). Additional applications were performed to abolish DC. Atrial fibrillation recurrence was evaluated after 3, 6, and 12 months with ECG and 24 h Holter recordings. Results were compared with a prior group of consecutive patients that underwent cryoablation without DC testing (adenosine-). The adenosine+ group consisted of 36 patients (78% male, 61 ± 10 years, paroxysmal AF 86%). ***Dormant conduction was found in 42% of patients (15/36) and 14% of PVs (20/143). Multivariate analysis showed that PV isolation during the first freeze independently reduced DC risk (OR = 0.064, P < 0.01). After 12 ± 1 months, 11 (83%) of adenosine+ patients had no AF-recurrences, compared with 37 (60%) of adenosine- patients (n = 62, 70% male, 59 ± 11 years, 90% paroxysmal AF, P = 0.02). Ablation with DC treatment independently reduced the risk of AF-recurrence (OR = 0.26, P = 0.02).


CONCLUSION
Incorporating a 30-min waiting period after cryoballoon ablation increases the incidence of DC compared with previous results. Absence of PV isolation during the first freeze is associated with an increased risk of late DC. Treatment of this DC seems to improve outcome.