Local changes in conduction velocity in the left atrium of atrial fibrillation patients undergoing pulmonary vein isolation

Abstract

Abstract Background Electro-anatomical maps are standardly used to visualize anatomy and electrophysiological properties of the left atrium (LA) during pulmonary vein isolation (PVI) in atrial fibrillation (AF) patients. Purpose We sought to describe local differences in atrial conduction velocities (CVs), as a proof-of-principle, to study its association with tissue heterogeneity. We hypothesize that the variation and heterogeneity in these velocities throughout the LA carry important prognostic and diagnostic information, reflect the extent of remodeling and, in the future, might discern different subtypes of AF and treatment outcome. Methods We included AF patients who underwent PVI for the first time during 2021-2022. Electro-anatomical maps (EAMs) during sinus rhythm were acquired during the procedure and single data-points were projected on the patient-specific EAM-derived mesh of the LA. Patients 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) and were followed-up for 6 to 12-months. We determined unipolar voltages, activation times and computed local CVs for these patients. The CVs were normalized for each patients and reported as the median CV for each region containing enough points. Results We included 12 patients: 6 with paroxysmal and 6 with persistent AF. Patients in the paroxysmal group had larger median activation times and median CVs compared to the persistent group. The variability in voltage, activation time and CV was twice as large in the paroxysmal group (Table 1). Figure 1 displays an example of an electro-anatomical reconstruction of the LA of a paroxysmal AF patient showing the local median conduction velocity from an anterior and posterior view (Figure 1A and 1B) and the variance and distribution of median CV (Figure 1C). In this patient, we observed large local CV differences, which might reflect tissue heterogeneity (e.g. fibrosis). Conclusion We provided a proof-of-principle demonstrating that, with the use of conventional electro-anatomical maps, important information on heterogeneity and variance in local CVs can be quantified. We found a large variability in CV within and between patients. This can help discern different AF subtypes and might contribute to understanding different arrhythmogenic substrates and treatment outcome differences.