From St George to EASY-WPW: comparative validation of two ECG algorithms for accessory pathway localization
From St George to EASY-WPW: comparative validation of two ECG algorithms for accessory pathway localization
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Original abstract
Abstract Introduction/Background Accurate localization of accessory pathways (APs) from baseline ECG is crucial for planning ablation in Wolff–Parkinson– White patients (WPW). The EASY-WPW algorithm, published in 2023, offers a simplified stepwise approach, but its performance relative to other classic AP location algorithms, such as the St. George’s algorithm, is yet to be extensively validated Aim To compare the real-world diagnostic performance of EASY-WPW and the St George algorithm for AP localization, using electrophysiologic (EP) findings as the reference. Methods We retrospectively analysed consecutive patients with WPW pattern who underwent successful AP ablation at a Portuguese tertiary centre between 2021–2024. Pre-excitation ECGs were independently classified using EASY-WPW and St George algorithms. AP location from EP study was coded into seven segments (right/left antero-, postero- and lateral). Exact seven-segment localization and grouped right/left and septal/free-wall categories were compared. Accuracy, segment-wise sensitivity and positive predictive value (PPV) were calculated. Paired accuracies were contrasted with McNemar tests, to assess for significant differences between algorithms in AP location. Results Of 154 eligible patients, 147 had complete ECG and EP data (mean age 33.1 ± 17.7 years; 71% male; 29% <18 years). EASYWPW correctly identified the exact AP segment in 81/147 cases (55%), versus 54/147 (37%) with St George (McNemar p=0.001). Macro-averaged sensitivity and PPV across the seven locations were higher with EASY-WPW (53% and 52%) than with St George (39% and 36%). Right- versus left-sided classification was similar (73% vs 74%; p=0.86). However, EASY-WPW more accurately distinguished septal from free-wall pathways (80% vs 60%; p<0.001), with higher sensitivity for septal APs. Conclusion In this cohort, EASY-WPW showed moderate but significantly better performance than the St George algorithm for detailed AP localization, while maintaining comparable side (right/left) determination and clearly superior septal/free-wall discrimination. Although its use should be exercised with caution, given its moderate accuracy, these findings provide external validation of EASYWPW as a practical ECG tool foraccessory pathway localization, including in mixed adult–paediatric populations and in settings with limited electrophysiology experience.