16-25: Left atrial conduction delay as a marker of electroanatomical scar in patients undergoing pulmonary vein isolation: results from the SCAR-AF study

Introduction: Left atrial fibrosis is thought to be associated with outcome after pulmonary vein isolation (PVI) in atrial fibrillation (AF) patients. Aim of this study is to determine (1) the incidence of bipolar left atrial (LA) electroanatomical scar (EA-S) in patients with AF undergoing PVI and (2) its correlation with LA conduction delay.

Methods: Consecutive AF patients referred for PVI using an electroanatomical 3D mapping system were enrolled. The map was acquired during SR. Patients in which SR could not be restored after 2 DC cardioversion were excluded. After double transseptal puncture “time to LAA” was determined (TTLAA: P wave begin to first intracardiac LAA activation measured with a circumferential mapping catheter (CMC)). EA-S was defined as an area with a bipolar amplitude <0.5 mV. Two groups were defined: group A, without EA-S, and group B, with presence of left atrial EA-S.

Results: One hundred patients (61 male, 69 ± 9 years, 41 paroxysmal AF (PAF), 59 persistent AF (persAF)) were enrolled, 49/100 had no EA-S, group A, 51/100 presented an EA-S, group B. In group B patients were significantly older (74 ± 6 vs. 64 ± 9 years; p < 0.001), were mostly female (29/51 (57%) vs. 10/49 (20%), p < 0.001) and had a history of arterial hypertension (44/51 (86%) vs 30/49 (61%), p < 0.001). EA-S were localized in the left atrial anterior wall in 48/51 patients (94%), while EA-S in the lateral wall were rare (6/51 pts, 11,8%). Septal, posterior, roof and inferior EA-S were identified in the 65%, 39%, 39% and 22% of patients of group B, respectively. TTLAA was significantly longer in patients with LA-EA-S (122 ± 43 vs. 84 ± 22 ms, group B and group A, respectively p < 0.001). P wave duration was longer in group B (133 ± 28 vs. 119 ± 18 ms, p = 0.009). PVI was achieved in all patients without major complications. Follow up is ongoing to clarify the clinical role after a PVI procedure of EA-S and interatrial conduction delay.

Conclusion: Age, female sex and hypertension are risk factors for EA-S. Sinus rhythm conduction time to LAA is significantly longer in patients presenting with left atrial EA-S.