Transient Ventricular Capture Loss Following Alcohol Septal Ablation in Left Bundle Branch Area Pacing: A Case Report

BACKGROUND: Alcohol septal ablation (ASA) is an established therapy for symptomatic hypertrophic obstructive cardiomyopathy (HOCM) but may cause conduction disturbances. Data on interactions between ASA and left bundle branch area pacing (LBBAP) leads are limited. CASE SUMMARY: A 70-year-old woman with complete AV block and dual-chamber pacemaker with LBBAP developed severe LVOT obstruction (Valsalva 93.3 mmHg) with syncope and dyspnea. ASA of the first septal branch (4 mL 95% ethanol) caused immediate hypotension and transient loss of ventricular capture due to abrupt LBBAP threshold rise, requiring temporary pacing. Increasing output to 5 V/1.0 ms restored capture. Threshold peaked at 3.25 V/0.4 ms and normalized within 3 days. Imaging showed ablation-lead overlap. LVOT gradient fell to 14.9 mmHg at 2 weeks. CONCLUSION: ASA can transiently compromise LBBAP capture when the ablation zone is adjacent to the lead; careful imaging and peri-procedural backup pacing are advised.