Heterogeneity in voltage and activation time in the left atrium of atrial fibrillation patients undergoing pulmonary vein isolation

Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): ITEA 3 Symphony project Introduction Electro-anatomical maps are standardly used to visualize anatomy and electrophysiological properties of the left atrium during pulmonary vein isolation (PVI) in atrial fibrillation (AF) patients. We sought to describe heterogeneity in atrial voltage and activation time, as a proof-of-principle, to study its association with treatment outcome. Therefore, we projected all data-points from electro-anatomical maps to the CT scan meshes of the left atrium and calculated median voltage and activation time in patients with paroxysmal or persistent AF undergoing first PVI ablation. We hypothesize that the variation and heterogeneity in these parameters throughout the left atrium carry important prognostic and diagnostic information and can be used to discern different subtypes of AF. Methods We included AF patients who underwent PVI for the first (cohort I) and second time (cohort II) during 2021-2022. Electro-anatomical maps during sinus rhythm were acquired before and after the ablation procedure and were projected on the patient-specific CT-scan-derived mesh of the left atrium. Patients underwent 6 to 12-month follow-up and were classified as persistent (AF lasting longer than 7 days and usually requiring electrical cardioversion) and paroxysmal (self-terminating AF episodes, lasting shorter than 7 days, mostly shorter than 24 hours). We determined bipolar voltages and activation times for persistent and paroxysmal AF patients in each cohort. In addition, we compared global left atrial voltage and activation times pre- and post-PVI. Results Our study population consisted of 24 patients: 14 patients in cohort I and 10 patients in cohort II. Summary of baseline and voltage and activation times can be found in Figure 1. In both cohorts, patients with persistent AF showed a trend towards a lower median LA voltage (Figure 1), but not a longer median atrial activation time. Paroxysmal patients showed more heterogeneity (wider IQR) in both voltage and activation times compared to persistent AF patients. Figure 2 displays a typical example of an electro-anatomical reconstruction of a paroxysmal AF patient pre- and post-second-PVI where the local heterogeneity can be observed - after the ablation, higher voltages and shorter activation times were observed. Conclusion We provide a proof-of-principle demonstrating that with the use of conventional electro-anatomical maps, important information on heterogeneity and variance in local voltage and activation time can be quantified. This quantification can help discern different AF subtypes and might contribute to understanding different arrhythmogenic substrates and treatment outcome differences.