Coronary venous occlusion by prior catheter ablation within the coronary venous system: a potential risk of precluding branch mapping and adjunctive chemical ablation.

We present case series of coronary vein occlusion by prior radiofrequency (RF) ablation within the coronary venous system (CVS). Case 1 was treated with endocardial RF ablation at the anatomically adjacent site to the earliest activation site identified by mapping of the annular branch which branched off proximally to the occluded site. In Case 2, attempted ethanol infusion to the septal perforator could not be performed due to occlusion of the CVS at the point where RF energy was delivered during the prior procedure. Our case series raise an issue regarding the workflow of ablation therapy for epicardial/intramural ventricular arrhythmias.