Wolff Parkinson White syndrome: Validation of an algorithm for identifying accessory pathway in children

Background Wolff Parkinson White syndrome is responsible of junctional tachycardia and potentially sudden death in children. Precise location of accessory pathway (AP) is crucial to increase safety and success rate of ablation procedures. Known ECG localization algorithms have limited accuracy in children close to 50%. Objective The aim of study was to evaluate a new ECG algorithm relying on maximal pre-excitation (EMP) in children. Methods ECG with EMP (ventricular activation secondary to AP without His bundle activation), induced by atrial pacing or adenosine test/vagal maneuver, was prospectively recorded during an electrophysiological study in 90 consecutive children under 16, in 3 tertiary centers between 2008 and 2020. 3 blinded investigators (1: expert rythmologist, 2: pediatric cardiologist and 3: pediatric cardiologist in training) tested a new algorithm based on EMP to predict AP location and 2 validated control algorithms, from Arruda and Min Baek, relying on basal pre-excitation. Predicted locations were matched with ablation-verified AP location. Sensibility, specificity, negative/positive predictive values and reproducibility, defined as level of agreement between investigators in determining AP location, were evaluated. Results AP were Left sided in 38%, septal in 47% and right sided in 16%. With the new algorithm, predictive accuracy for the 9 exact locations was 91%, 89% and 90% for investigator 1, 2 and 3, respectively. Sensibility was 80-100% for right sided, 95–100% for left sided and 62-100% for septal AP. Concordance between investigators was excellent (k ≥ 0,86). The accuracy for the reference algorithms remain poor (45% for Arruda and 51% for Min Baek) with less concordance between investigators. Conclusion Our new algorithm based on EMP allows accurate and easy to use localization of AP in children. This algorithm can be employed before cardiac catheterization and can allow better evaluation of the benefit/risk ratio of the intervention.