PO-03-049 SUBACUTE MIGRATION OF LEFT BUNDLE BRANCH PACING LEAD INTO THE LEFT VENTRICLE

Abstract

RV pacing is associated with increased risk for systolic dysfunction. Conduction system pacing has emerged as an alternative. His bundle pacing is limited by higher capture threshold, reducing battery life, and concerns of increasing thresholds over time. LBBP is a promising alternative, however limited data exist on associated complications. We report a case of LBBP complicated by subacute migration into the LV presenting with increasing threshold. A 78 yoM with symptomatic bradycardia and chronotropic incompetence referred for PPM underwent implantation of DC-PPM with left bundle lead. A Medtronic SelectSecure 3830 lead was advanced into a C315 sheath and positioned at the LV septum. Pace mapping defined a candidate site for LBBP (W in V1). Lead was screwed into the septum. Unipolar impedance prior to deployment was 820Ω. After 5 turns paced QRSd 140ms with qR morphology in lead V1, R waves 12.4mV, unipolar impedance 760Ω, threshold 0.75V at 0.4ms. This was accepted as nonselective LBBP. He began to have chest thumping on POD 3. Device showed elevated ventricular threshold, decreasing impedance, and stable sensing. ECG showed broad notched R wave in V1 consistent with LV pacing. CT revealed migration of the lead, coursing through the IVS into the LV myocardium with tip terminating along the inferior LV wall. Lead tip was possibly puncturing through the myocardium and within the epicardial fat. There was no effusion Lead was removed with manual traction in the EP suite. Heart border remained unchanged on fluoroscopy. Transthoracic echo showed no effusion. New lead was positioned with active fixation in the RV apical septum away from the prior position. Lead showed suitable parameters without diaphragmatic stimulation. LBBP can be an alternative to HB, RV, and CRT pacing. LBBP involves placing the lead deep within the IVS and close to the LV subendocardium. Septal perforation is often recognized during the procedure, however, the risk of late perforation must be considered. In our case, timing of lead migration is unclear as parameters during implant suggested adequate LB capture but reported diaphragmatic capture at day 3, before threshold increase. It demonstrates important findings:1.Acute decrease in unipolar impedance may not be a sensitive marker for septal perforation as it did not change appreciably in our case; 2.ECG/CXR in follow up can help identify lead migration; 3.Migrated leads can be safely removed in the EP suite without need for surgical backup