Characterization and Localization of Focal Atrial Tachycardia in Patients With Adult Congenital Heart Disease

BACKGROUND In patients with structurally normal hearts, algorithms using surface electrocardiographic P-wave morphology are helpful to predict focal atrial tachycardia (FAT) location. However, these algorithms have not been formally assessed in patients with adult congenital heart disease (ACHD). OBJECTIVES This study sought to assess the efficacy of FAT-location prediction algorithms in an adult population of patients with ACHD. METHODS In this single-center retrospective cross-sectional study, FAT P-waves were classified as: 1) positive; 2) negative; 3) isoelectric; or 4) biphasic. FAT ablation sites identified by electroanatomic mapping were grouped by region: right atrium (RA), paraseptal (PS), and left atrium. Accuracy of P-wave classification criteria to predict FAT region were determined. RESULTS Thirty FATs were assessed in 29 patients (mean age 47 f 16 years, female 55%, and prior surgical repair in 83%): RA FAT sites-crista terminalis (n =14), Fontan baffle (n = 3), nonseptal tricuspid annulus (n = 1); PS FAT sites-PS tricuspid annulus (n = 2), coronary sinus ostium (n = 3), foramen ovale (n = 1); and left atrial FAT sites-mitral annulus (n = 2), right superior pulmonary vein (n = 1), left atrial appendage (n = 3). A negative or (f) P-wave in V1 had a 100% specificity for RA origin. Other P-wave morphologies in lead V1 poorly predicted atrial origin. All P-wave morphologies in lead aVL had low sensitivity and specificity for atrial origin. CONCLUSIONS The vast majority of FATs observed in patients with ACHD originate from origins common to those with normal hearts rather than foci unique to ACHD. However, applying algorithms established in patients with normal hearts using P-wave morphology to localize FAT only variably predicts FAT origin in our cohort of ACHD patients. (JACC Clin Electrophysiol. 2025;11:120-131) (c) 2025 by the American College of Cardiology Foundation.