PO-04-013 A CASE OF INTERMITTENT ANODAL CAPTURE AFTER LEFT BUNDLE AREA PACING

Abstract

Left bundle area pacing (LBAP) is emerging as a reliable form of conduction system pacing (CSP) that can be beneficial in cardiac resynchronization therapy (CRT). We present a case of intermittent anodal capture noted after septal lead insertion in a patient undergoing LBAP. N/A An 80-year-old male with hypertension, COPD, and sick sinus syndrome who had undergone dual chamber pacemaker implantation in 2007, had known atrial lead fracture since 2020, now presented with heart failure syndrome (EF dropped from 60% to 15%). A coronary angiogram showed non-obstructive coronary artery disease. As such decision was made for fractured atrial lead extraction and implantation of new atrial lead to provide AV synchrony as well as upgrading the device to biventricular ICD, given the persistent low ejection fraction. During the procedure, coronary sinus anatomy was found unsuitable for lead insertion, and hence LBAP was opted for instead. LBAP lead was placed at an appropriate septal location with QRS morphology in lead V1 changing from an initial “W” pattern to notching as the lead was advanced with an appropriate rise in thresholds. QRS duration decreased to 144 milliseconds; however, intermittently variable QRS morphologies were noted. In LBAP, anodal capture can occur during bipolar configuration where the tip of the lead (cathode) is capturing the left bundle, and the ring (anode) starts capturing the right bundle area. This happens when the lead is penetrating the interventricular septum (IVS) enough for the ring portion to come into contact with the right septal area. In our patient, note the different QRS morphologies in lead V1 (Panel A). The right bundle morphology QRS (marked red) is the expected result of LB pacing, while the left bundle morphology QRS (marked green) is likely occurring from concurrent anodal capture of the right bundle. The QRS duration is noted to be somewhat narrower when the left bundle morphology is present, as would be expected when both bundles are simultaneously captured (LB by the tip and RB by the ring) (Panel B). It is unclear whether such a phenomenon as anodal capture of the RB along with concurrent LB pacing can be of any clinical significance and needs further research.