Biatrial tachycardia due to conduction recovery of left atrial anterior roof lesion created by vein of Marshall ethanol infusion

A 77-year-old man underwent pulmonary vein isolation and cavotricuspid isthmus ablation for paroxysmal atrial fibrillation and typical atrial flutter.Eleven months later, recurrent atrial fibrillation required a second procedure.Left atrial (LA) posterior wall isolation and vein of Marshall (VOM) ethanol infusion were performed for roofdependent atrial tachycardia (AT) and Marshall bundle (MB)-related triggers.A third procedure was required for recurrent AT.After completion of the anterior mitral line, an induced MB-related AT was terminated by VOM ethanol infusion, and the LA anterior roof area appeared electrically isolated.However, two weeks later, a rapid AT recurred and a fourth procedure revealed conduction recovery across the previously isolated LA anterior roof area, resulting in a counter-clockwise biatrial tachycardia.Radiofrequency ablation at the LA ridge and anterior wall terminated the AT and re-isolated the LA anterior roof area.This case demonstrates that lesions created by VOM ethanol infusion, particularly those extending toward the LA roof, may not always be durable.Learning objective : Vein of Marshall (VOM) ethanol infusion is widely used to eliminate Marshall bundlerelated atrial tachycardia.When VOM ethanol infusion creates isolation extending toward the left atrial anterior roof, additional endocardial radiofrequency ablation should be co nsidered to ensure durable block and prevent arrhythmia recurrence.