Non-Invasive Programmed Stimulation to Confirm Left Bundle Branch Capture During Outpatient Follow-Up: a Case Report

Left bundle branch area pacing (LBBAP) is a physiological pacing technique that ensures near-normal ventricular activation. However, confirming left bundle branch (LBB) capture during follow up can be challenging when standard criteria are inconclusive. This report describes the use of non-invasive programmed stimulation (NIPS) via a pacemaker programmer to confirm LBB capture in an outpatient setting. We describe a 70-year-old Caucasian male who received a dual-chamber pacemaker (Zenex DR, Abbott, Sylmar, CA, USA) for symptomatic paroxysmal 2:1 atrioventricular block with a left ventricular ejection fraction of 48%. One month after implantation, LBBAP capture could not be confirmed using conventional criteria because of atypical QRS morphology. NIPS was safely performed using the device programmer. Programmed stimulation with extra stimuli induced a transition from non-selective to selective LBB capture, demonstrated by prolongation of the V1 R-wave peak time and changes in QRS morphology. No arrhythmias occurred during the test. This case illustrates the practical application of the principles of programmed stimulation in an outpatient setting to confirm LBB capture, especially in ambiguous cases where conventional criteria are inconclusive.