Epicardial electrical dissociation with endocardial conduction following deployment of an epicardial left atrial appendage closure device.

Abstract

The left atrial appendage (LAA) accounts for 90% of clots in non-valvular atrial fibrillation (AF)1 and contains anisotropic tissue at the junction with the left atrium (LA) which may result in the initiation and maintenance of AF.2 Minimally invasive epicardial closure may reduce the risk of thromboembolism and electrically isolate the LAA from the LA. Complete endocardial LAA electrical isolation using radiofrequency (RF) catheter ablation has been shown to reduce the recurrence rate of AF to 15% compared with 68% for focal ablation of LAA triggers and 74% with no ablation.3 Despite this early LAA reconnections (within 30 min) may occur in 50–70% of endocardial isolations requiring further RF ablation with an acute isolation rate of over 90%.4 Late LAA reconnections (up to 3 months) may occur in almost 30% of complete endocardial isolations.5 Mechanical exclusion of the LAA may reduce the production of important peptides such as atrial natriuretic peptide which plays a key role in the maintenance of blood volume and blood pressure.6 When considering closure of the LAA, it is important to understand the complex anatomy and electrical innervation of this structure. Although epicardial LAA isolation has been shown to result in epicardial conduction block,7 we describe a case of acute epicardial electrical isolation with continued endocardial conduction. This may imply that the use of an epicardial closure device does not always result in complete electrical isolation which may reflect the complex anatomy of the innervation of the LAA.