High efficacy and safety of endocardial pulsed electrical field ablation via contact force-controlled catheters for mitral isthmus ablation

Abstract Background A new technology of a pulsed field generator enables established contact force-controlled radiofrequency (RF) catheters to apply point by point monopolar pulsed electrical field (PEF) energy for linear lesions in atrial fibrillation (AF) ablation. Purpose We evaluated this novel monopolar PEF ablation technique for creating lateral mitral isthmus ablation lines in case of perimitral flutter or complex AF patients non responder to pulmonary vein isolation (PVI). Methods Patients (n=44, age 65±11 years) referred for ablation/re-ablation of AF with spontaneous or inducible perimitral atrial flutter (n=34, 77%) or persistent AF and severe enlarged atrium (n=7) or de novo longstanding persistent AF (n=3) without signs of atrial fibrosis were included in our patient cohort for lateral mitral isthmus ablation with PEF applications. After 3D high density voltage mapping of the left atrium with multipolar microelectrode catheters, and confirmation/completion of PVI, an endocardial lateral mitral isthmus line was performed. Using contact force sensing catheter, 25A PEF energy pulses were applied targeting a minimum of 10g contact force and an interlesion distance ≤5mm. Before PEF application 0.2 mg nitroglycerin was intravenously injected. If the inferolateral mitral isthmus line to the left inferior pulmonary vein could not be blocked, a more superior lateral line to the left superior pulmonary vein was performed. If the mitral isthmus could not be blocked by endocardial PEF application or conduction recurred after adenosine injection an additional epicardial ablation via RF application in the coronary sinus was performed. Results Exclusively endocardial PEF application blocked the lateral mitral line in 37 out of 42 cases (88%) with 23±14 PEF applications. After an unsuccessful inferior lateral mitral line, in 34% of cases a second superior lateral mitral line have to be performed. Only in five cases additional epicardial RF applications via coronary sinus were necessary to complete the mitral isthmus block. Block time between superior lateral mitral anulus and infero lateral coronary sinus was 196±48 ms. One pericardial tamponade which could be successfully drained, and no other serious complication occurred throughout all procedures (no ST segment elevation, no tamponade requiring surgery, no cerebrovascular event). Limited follow-up will be available at the time of presentation. Conclusion Blockade of left atrial mitral isthmus line with PEF application via contact force-sensing catheters for ablation of complex atrial fibrillation patients is very efficient and safe. Especially the high efficacy of exclusively endocardial PEF application for creation of a lateral mitral isthmus block in most patients is very promising. However, the long term permanence of the linear lines have to be awaited.