Atrioventricular conduction properties in patients with prolonged pauses undergoing ablation of longstanding persistent atrial fibrillation: do pauses during atrial fibrillation matter?

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Atrioventricular (AV) conduction disturbances have often been considered as an etiology of prolonged pauses during atrial fibrillation (AF). We aimed to test whether there was a significant difference in the AV conduction properties between patients with and without clinically significant pauses who underwent ablation of longstanding persistent AF. Ninety-nine patients undergoing ablation of longstanding persistent AF were divided into three groups according to the extent of pauses documented on the ambulatory electrocardiogram during AF; patients without pauses (n = 25), with pauses of <3 s (n = 52), and with pauses of ≥3 s (n = 22). The AV conduction properties, heart rate variability, and bradycardia-related symptoms after conversion to sinus rhythm were compared across the three groups plus a control group (n = 35). Sinus conversion was achieved in all patients after ablation. No differences were found across the groups in the AV conduction properties including the AH and HV intervals, AV nodal effective refractory period, or Wenckebach point. A male gender (β = 0.32; p = 0.0016), structural heart disease (β = 0.24; p = 0.02), and the AA interval right after ablation (β = 0.35; p = 0.0014), rather than the AV conduction properties, were independent determinants of the longest normal RR interval during AF. No patients experienced any bradycardia-related symptoms after ablation. No AV conduction abnormalities were necessarily identified after the ablation even among the patients suspected of having an AV conduction disturbance during AF.