Atrial functional substrate mapping predicts the critical isthmus of left atrial reentrant tachycardia in atrial fibrillation

Abstract Background Atrial tachycardia (AT) and atrial fibrillation (AF) are common arrhythmias observed in patients with structural atrial remodeling. Following AF ablation, a subset of recurrences occurs as ATs. Also the ablation lesions created during AF ablation may themselves contribute to the development of AT recurrence. Functional substrate mapping (FSM) may facilitate the identification of slow conduction areas that represent critical atrial regions, thereby enabling accurate localization of AT and the creation of effective ablation lesions in these patients. Purpose In this study we aimed to investigate the relationship between the critical isthmuses (CIs) of left ATs and the characteristics of FSM in AF patients with underlying low-voltage areas. Methods A total of 52 patients that underwent catheter ablation for AF using high-density three-dimensional (3D) electroanatomical mapping, in whom left AT was inducible, were enrolled. Voltage map and isochronal late activation mapping were created during sinus/paced rhythm to detect deceleration zones (DZ). Pulmonary vein isolation was performed in all patients. After induction of AT, activation mapping was performed to detect CI of the tachycardia. Additional ablation was performed mainly targeting critical sites of reentry as well as DZs. Recurrence was defined as the detection of AT/AF (≥30 s) after the blanking period (>3 months) following the ablation procedure. Results In 52 patients (mean age 66.1 ± 8.4 years; 73.1% female; 71.1% persistent AF), 61 left ATs were induced, of which 36 (59%) were macroreentrant and 25 (41%) were localized reentrant. Voltage mapping during sinus rhythm revealed low-voltage area of 30.5 ± 18.4 % of the left atrium. The mean number of DZs per atrium was 1.3±0.6. DZs were most frequently located on the anterior wall and were predominantly observed within the voltage range of 0.1–0.5 mV (Figure 1). The positive predictive value of DZs to detect CI of inducible ATs is 78.7%. During a mean follow-up of 17.8 ±10.4 months, freedom from atrial tachyarrhythmia was 77% (Figure 2). Conclusions DZs identified by FSM during sinus/paced rhythm predict the CI of AT. Ablation of these areas in addition to pulmonary vein isolation may improve freedom ATa recurrences after index ablation.Figure 1Figure 2