New algorithm for accessory pathway localization focused on screening septal pathways in pediatric patients with Wolff-Parkinson-White syndrome.

BACKGROUND: Published algorithms for accessory pathway localization in Wolff-Parkinson-White (WPW) syndrome are inaccurate in pediatric patients, especially for septal pathways. OBJECTIVE: We aimed to develop a new algorithm that is sensitive for septal pathways and more applicable in pediatric patients. METHODS: In 120 patients (mean age: 11.7 ± 3.9 years) who underwent catheter ablation for WPW syndrome, the candidate criteria for new algorithm were searched by comparing electrocardiography parameters and accessory pathway locations. A new algorithm was designed to increase the sensitivity for septal pathways. For validation, 142 patients (mean age: 15.8 ± 3.7 years) were additionally evaluated. New and published algorithms were applied to electrocardiography of 262 patients and the results were compared. RESULTS: The new algorithm achieved its best discrimination by combining several parameters together in each step: (1) QRS polarity in V1 and QRS shape in lead I for left/right discrimination, and (2) delta wave polarity in V1, QRS transition in precordial leads, and delta wave polarity in lead III for septal pathway screening. The new algorithm showed higher sensitivity for septal pathways (95.7%) than 7 published algorithms (average: 62.1%), with satisfactory positive predictive value (77.9%). Delta wave polarity in V1 among septal pathways and QRS axis among right anteroseptal pathway showed age-related trend; this could be the reason for the lower accuracy in localizing septal pathways in children. CONCLUSION: The inaccuracy of published algorithms in pediatric patients is due to the age-related trend in the electrocardiography of septal pathways. The new algorithm was superior for localizing septal pathways in pediatric patients.