Arrhythmic substrate in pulmonary vein isolation reprocedures in the era of the close protocol

FUNDING ACKNOWLEDGEMENTS: Type of funding sources: None. INTRODUCTION: The CLOSE protocol was developed as a radiofrequency ablation strategy that would result in the safe creation of durable pulmonary vein isolation (PVI) leading to improved outcomes. The aim of the protocol is to enclose the PVs with stable, contiguous and ablation index (AI) guided lesions. PURPOSE: We analyze the arrhythmic substrate found in patients undergoing PVI reprocedure after a first CLOSE-PVI procedure and compare it to that observed in PVI reprocedure in patients who underwent a first non-CLOSE-PVI procedure. METHODS: Patients undergoing a PVI-reprocedure after a first CLOSE-PVI procedure (35W, AI 450 for the anterior wall and 350 for posterior wall) were prospectively included (CLOSE-group). During the reprocedure a detailed electroanatomical map with multielectrode catheters was obtained in all patients. The number of reconnected PVs and segments was assessed. In patients with left atrial flutter (AFl), the circuit was defined by activation and entrainment mapping. These data were compared to those observed in a historic control group of PVI reprocedures after a first non-CLOSE-PVI procedure (non-CLOSE-group; 21 reprocedures among 157 first PVI procedures). RESULTS: Among 352 patients undergoing a first CLOSE-PVI, 27 (74.1% male, 57±8.6 years) underwent a PVI reprocedure. 74% (20 patients) showed at least 1 PV reconnected vs 100% in non-CLOSE group; p=0.012. Among the 7 patients without PV reconnection (PVR) perimitral AFl was found in 2 patients and a roof dependent AFl was observed in 1 patient. In the remaining 4 patients no specific substrate or trigger was observed. Among patients showing PVR, no differences were observed in terms of mean number of reconnected PVs [2(1-2) vs 2(1-3) respectively; p=0.751] or segments [2(1-2) vs 2(2-4) respectively; p=0.895) compared to the non-CLOSE group. CONCLUSION: PVR remains the main substrate in patients undergoing atrial fibrillation (AF) ablation reprocedure after a first CLOSE-PVI. However, a significantly higher proportion of patients showed persistent PVI without a specific arrhythmic substrate or trigger for AF; which makes it necessary to define new strategies to improve rhythm control in these patients.