Abstract
BACKGROUND: Left atrial appendage (LAA) membranes are rare congenital anomalies of uncertain clinical significance, often discovered incidentally during imaging or interventional procedures. CASE SUMMARY: A 50-year-old man with paroxysmal atrial fibrillation presented for LAA occlusion device implantation and atrial fibrillation ablation. Transesophageal and intracardiac echocardiography revealed a membrane completely occluding the LAA ostium, as confirmed by Doppler imaging, fluoroscopy, and electroanatomical mapping. No LAA occlusion device was implanted, but AF ablation was successfully performed. The patient was in sinus rhythm and was asymptomatic at follow-up. DISCUSSION: A total of 13 cases of LAA membranes have been reported in the literature. Their relationship with atrial arrhythmias and thromboembolism remains unclear. This case demonstrates the use of electroanatomical mapping to confirm the atrial myocardial characteristics of the membrane. TAKE-HOME MESSAGES: Anatomic variants such as LAA membranes underscore the importance of advanced imaging and mapping to ensure procedural safety and success in complex cardiac interventions.