Restoration of Sinus Rhythm by Incarceration, not Elimination, of Focal Atrial Tachycardia in Left Atrial Substrate Post Atrial Fibrillation Ablation

Abstract

While diseased regions of the atrial body commonly behave as a substrate maintaining atrial fibrillation (AF), these areas can uncommonly behave as trigger foci for atrial tachycardia (AT),1 particularly after previous ablation. Unlike venous triggers, the goal of ablation for these focal ATs is normally elimination of the tachycardia source, rather than complete isolation. We present a case of a difficult to ablate post–AF-ablation AT from the anterior left atrium (LA), in which sinus rhythm was restored by incarcerating the ongoing AT within a small, isolated region of LA myocardium. A 67-year-old man who underwent pulmonary vein isolation, electrogram-based LA ablation, and roof, left mitral and cavotricuspid isthmus ablation for permanent AF in 2002 and repeat ablation of recurrent paroxysmal AF in 2009 (details unavailable), was referred for a third ablation procedure for rate-controlled incessant AT (Figure 1A). Figure 1B shows intracardiac recordings on decapolar catheter in the coronary sinus and 3.5-mm externally irrigated tip ablation catheter in the LA during baseline AT (cycle length, 308 ms). Activation and entrainment mapping2 established the diagnosis of focal source AT arising from the ostium of the left atrial appendage (LAA) where ablation led to cycle length variation of >25% (range, 276 to 402 ms) – unstable AT (Figure 1C). Focal ablation at another site with substantial temporal gradient between the proximal and distal bipoles of the ablation catheter …