Background: Areas of conduction delay (CD) or conduction block (CB) are associated with higher recurrence rates after ablation therapy for atrial fibrillation (AF). Objective: Thus far, there are no reports on the quantification of the extensiveness of CD and CB at the pulmonary vein area (PVA) and their clinical relevance. Methods: Intraoperative high-density epicardial mapping of the PVA (interelectrode distance 2 mm) was performed during sinus rhythm in 268 patients (mean ± SD [minimum–maximum] 67 ± 11 [21–84] years) with and without preoperative AF. For each patient, extensiveness of CD (conduction velocity 17–29 cm/s) and CB (conduction velocity <17 cm/s) was assessed and related to the presence and type of AF. Results: CD and CB occurred in, respectively, 242 (90%) and 183 (68%) patients. Patients with AF showed a higher incidence of continuous conduction delay and block (CDCB) lines (AF: n = 37 [76%]; no AF: n = 132 [60%]; P =.046), a 2-fold number of lines per patient (CD: 7 [0–30] vs 4 [0–22], P <.001; CB: 3 [0–11] vs 1 [0–12], P =.003; CDCB: 2 [0–6] vs 1 [0–8], P =.004), and a higher incidence of CD or CB lines ≥6 mm and CDCB lines ≥16 mm (P =.011, P =.025, and P =.027). The extensiveness of CD, CB, and CDCB could not distinguish between the different AF types. Conclusion: Patients with AF more often present with continuous lines of adjacent areas of CD and CB, whereas in patients without AF, lines of CD and CB are shorter and more often separated by areas with normal intra-atrial conduction. However, a considerable overlap in the amount of conduction abnormalities at the PVA was observed between patients with a history of paroxysmal and persistent AF.

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Heart Rhythm
Department of Cardiology

Mouws, E.M.J.P, van der Does, J.M.E, Kik, C, Lanters, E.A.H, Teuwen, C.P, Knops, S.P, … de Groot, N.M.S. (Natasja M.S.). (2019). Impact of the arrhythmogenic potential of long lines of conduction slowing at the pulmonary vein area. Heart Rhythm. doi:10.1016/j.hrthm.2018.10.027