Abstract
BACKGROUND: Left bundle branch area pacing (LBBAP) is increasingly adopted as a physiological pacing strategy. Deep septal lead deployment, however, may occasionally result in unexpected vascular staining. CASE SUMMARY: A 70-year-old woman with advanced atrioventricular block and preserved ejection fraction underwent LBBAP. During contrast injection to assess septal lead depth, unexpected opacification of the left anterior descending artery and a septal perforator branch occurred, suggesting inadvertent vascular entry. The lead was promptly repositioned more proximally, achieving optimal electrical parameters. The patient remained asymptomatic, and follow-up echocardiography confirmed preserved ventricular function without pericardial effusion or hematoma. DISCUSSION: To our knowledge, this is the first report providing direct angiographic visualization of coronary opacification during LBBAP, highlighting the importance of septal vascular anatomy and imaging guidance. TAKE-HOME MESSAGES: Inadvertent vascular staining during LBBAP is rare and usually benign when promptly recognized. Angiographic contrast injection is useful to confirm lead position and detect unintended vascular entry.