138-05: Evidence for a correlation between rotor activity and atrial fibrosis in patients with atrial fibrillation

Abstract

Purpose: Despite significant progress in catheter techniques suboptimal ablation outcomes are observed for patients with atrial fibrillation (AF). This effect is potentially related to the standard approaches of most ablation techniques which mainly focus on anatomic rather than patient specific functional targets. Recently, two new ablation concepts have been introduced which are aimed on patient specific targets. First, stable electrical rotors and focal sources have been demonstrated to sustain AF. Therefore, the ablation of rotors has been associated in first studies with an improved clinical outcome in comparison to conventional ablation. Second, there is increasing evidence that atrial fibrosis can not only be considered as predictor for the ablation outcome but also as a primary disease driving AF. Along this line, atrial fibrosis could be a target for tailored ablation. The aim of this study is to investigate the correlation between rotor acticity and left atrial fibrosis in patients with AF. Methods: Patients that underwent redo procedure for AF using Focal Impulse and Rotor Mapping (FIRM) were analyzed for number and location of rotors and for degree and location of left atrial fibrosis. Left atrial (LA) voltage maps were generated during sinus rhythm after rotor and pulmonary vein isolation. Low voltage was defined as a signal amplitude < 0,5 mV. Fibrosis was categorized as stage 1 (<10% of the LA wall), 2 (≥10%- < 20%), 3 (≥20%- < 30%), and 4 (≥30%). Results: 42 patients (mean age 62 ± 9 years, 31 male) with recurrent AF (37 persistent, 5 paroxysmal) were included. There were 21 patients in stage 1 (50%), 7 in stage 2 (17%), 9 in stage 3 (21%) and 5 in stage 4 (12%). In patients with stage 1 we observed a mean number of RA rotors of 0.6 ± 0,7 (0–2) and LA rotors of 1.4 ± 0.9 (0–4), with stage 2 0.3 ± 0.5 (0–1) and 1.9 ± 0.7 (1–3), with stage 3 1.1 ± 1.1 (0–3) and 2.3 ± 1.0 (1–4) and with stage 4 0.6 ± 0.5 (0–1) and 3.0 ± 1.2 (2–5), respectively. We found significant more LA rotors (2.3 ± 1.0; 1–5) in patients with verification of LA fibrosis (stage 2–4) than in patients without relevant LA fibrosis (p = 0.04). A total of 29 out of 80 LA rotors (36%) in all patients were located in a spacial vicinity of a low voltage area. As expected, the number was higher in patients with LA fibrosis (59%), also depending on the degree of fibrosis (stage 2: 38%, stage 3: 57%, stage 4: 80%). Conclusions: Rotor activity has been identified in patients with and without LA fibrosis. However, more LA rotors have been observed in patients with LA fibrosis. Depending on the degree of fibrosis an increasing number of rotors have been found in spacial vicinity of LA fibrosis areas.