DEVELOPMENT AND VALIDATION OF AN ECG ALGORITHM FOR IDENTIFYING ACCESSORY PATHWAY ABLATION SITE IN WOLFF-PARKINSON-WHITE-SYNDROME

ECG Localization of Accessory AV Pathways. Introduction: Delta wave mo rphology correlates with the site of ventricular insertion of accessor y AV pathways. Because lesions due to radiofrequency (RF) current are small and well defined, it may allow precise localization of accessory pathways. The purpose of this study was to use RF catheter ablation t o develop an ECG algorithm to predict accessory pathway location. Meth ods and Results: An algorithm was developed by correlating a resting 1 2-lead ECG with the successful RF ablation site in 135 consecutive pat ients with a single, anterogradely conducting accessory pathway (Retro spective phase). This algorithm was subsequently tested prospectively in 121 consecutive patients (Prospective phase). The ECG findings incl uded the initial 20 msec of the delta wave in leads I, II, aVF, and V- 1 [classified as positive (+), negative (-), or isoelectric (+/-)] and the ratio of R and S wave amplitudes in leads III and V-1 (classified as R greater than or equal to S or R < S). When tested prospectively, the ECG algorithm accurately localized the accessory pathway to 1 of 10 sites around the tricuspid and mitral annuli or at subepicardial lo cations within the venous system of the heart. Overall sensitivity was 90% and specificity was 99%. The algorithm was particularly useful in correctly localizing anteroseptal (sensitivity 75%, specificity 99%), and mid-septal (sensitivity 100%, specificity 98%) accessory pathways as well as pathways requiring ablation from within ventricular venous branches or anomalies of the coronary sinus (sensitivity 100%, specif icity 100%). Conclusion: A simple ECG algorithm identifies accessory p athway ablation site in Wolff-Parkinson-White syndrome. A truly negati ve delta wave in lead II predicts ablation within the coronary venous system.