B-AB16-02 P WAVE MORPHOLOGY IN FOCAL ATRIAL TACHYCARDIA: AN UPDATED 2021 ALGORITHM TO PREDICT SITE OF ORIGIN

Abstract

The 2006 P wave morphology (PWM) algorithm was useful in predicting the origin of focal atrial tachycardia (AT). An updated algorithm was developed given advances in three dimensional(3D) mapping, potential limitations of PWM in separating paraseptal (PS) sites, and a renewed interest in the P wave in mapping non- pulmonary vein triggers in atrial fibrillation ablation. To report PWM from a series of PS AT, revise then prospectively evaluate a simplified PWM algorithm against a contemporary cohort with focal AT. The P wave morphology from a consecutive series of 67 patients with PS AT were analysed. PS sites included: CS ostium, perinodal, left and right septum, septal tricuspid annulus, superior mitral annulus and non-coronary cusp. Next the P wave algorithm was revised and prospectively evaluated by 3 blinded assessors. The PWM was not useful in separating PS sites. Generally the PS P wave was negative/positive, isoelectric/positive or isoelectric in lead V1 in 93% of cases. The P wave algorithm was prospectively applied to 30 consecutive patients with focal AT who underwent successful ablation. Foci (30) originated from right atrium (33.3%), left atrium (30%) and PS (36.7%). Using the P wave algorithm, the correct anatomic location was identified in 93%. Incorrect interpretation of the terminal positive P wave component(3) and initial negative P wave deflection(1) in lead V1 misidentified 4 paraseptal cases. The revised 2021 P wave morphology algorithm offers a simplified and accurate method of localising the responsible site for focal atrial tachycardia. The P wave remains an important first step in mapping atrial arrhythmias.