Hybrid convergent ablation: an evaluation of left atrial electroanatomical voltage maps

Abstract

Abstract Background Hybrid convergent ablation is an effective, emerging treatment for persistent atrial fibrillation (AF) (1). Minimally invasive surgical epicardial left atrial (LA) ablation is performed via a subxiphoid incision to ablate the posterior wall, within the limits of the pericardial reflections, before endocardial catheter ablation is performed primarily to complete pulmonary vein isolation. The overall aim is to create durable, transmural posterior wall ablation to target potential drivers that may sustain persistent AF. Purpose We evaluated electroanatomical maps obtained during endocardial ablation to determine the site and extent of LA posterior wall scar following epicardial ablation and whether this determines outcome in patients undergoing convergent ablation. Methods Patients who underwent Convergent ablation at a single UK cardiac centre (2012-2019) using CARTO-3 mapping system for endocardial ablation were included. Patients who had previous AF ablation were excluded. Low-voltage areas (LVAs) were manually measured using the CARTO-3 system and defined as areas <0.5mV on bipolar voltage maps (pulmonary veins were excluded). Scar location was classified by evaluating for presence and amount of LVA in each quadrant of the posterior LA wall. AF recurrence was evaluated at 12 months post-procedure. SPSS (v. 27) was used for statistical analysis. Results Of the 32 patients included, 7 patients experienced AF recurrence within 12 months post-procedure (21.9%). The average amount of posterior wall LVA following convergent ablation was 54.1% of posterior wall area and 5.8% of total left atrial area, neither of which were associated with 12-month AF recurrence (see Table 1). The presence and extent of LVAs in the upper quadrants were heterogeneous amongst patients and did not relate to AF recurrence. All patients displayed LVAs in the lower quadrants post-epicardial ablation, with the majority having LVAs occupying more than 50% of these quadrants. 96.8% had LVA on the inferior LA surface. In total, 75% of patients had a significant amount of LVA (defined as LVA occupying >50% of the quadrant area) in both lower posterior wall quadrants (see Figure 1) and this feature was associated with lower AF recurrence on multivariable Cox regression analysis (see Table 1). Conclusions Extensive scar was observed in the LA posterior wall in patients following epicardial convergent ablation. The presence of such scar, particularly in the lower regions of the posterior wall, may influence outcomes and be associated with reduced AF recurrence.Table 1Figure 1