Delayed Activation of the Left Atrial Appendage Following Catheter Ablation of Persistent Atrial Fibrillation: A Cause for Concern?

Abstract

Despite advances in catheter ablation of patients with persistent atrial fibrillation (AF), the ideal ablation strategy still is in evolution. It is known, however, that these patients fare poorly with pulmonary vein (PV) isolation alone.1 In an effort to improve outcomes, potential mechanisms of AF beyond the PVs have been targeted by left atrial linear ablation,2,3 ablation of complex fractionated atrial electrograms (CFAEs),4 ablation of ganglionated plexi, and a combination thereof. Recently, “stepwise ablation,” consisting of PV isolation, ablation of CFAEs, and linear ablation in an effort to terminate AF, has been reported to be highly effective in patients with persistent AF.5 However, extensive ablation may be associated with impairment of left atrial (LA) contractility. Although sinus rhythm may have been attained, altered LA activation and mechanical function may lead to AV dyssynchrony and an ongoing risk of thromboembolic complications. In this issue of PACE, Jiang et al. present their experience with extensive LA ablation in patients with persistent AF and resultant conduction delay into the left atrial appendage (LAA).6 Among 201 patients with persistent AF, LAA delay, defined as the activation of the LAA after the onset of the QRS complex on the surface electrocardiogram, was observed in 23 patients (11%) after the first ablation procedure. The ablation strategy included PV isolation followed by linear ablation along the roof, LA septum (from the mitral annulus to the rightsided PVs or the roof line), mitral, and cavotricuspid isthmi. Delay in LAA activation developed in nine of the first 26 patients (35%). Therefore, linear septal ablation was abandoned in favor of ablation of septal CFAEs in the remaining 175 patients. As a result, delay in LAA activation occurred in only five of these patients (3%). LAA activation delay also developed in nine of 45 patients (20%)