Post Pacing Interval Following Failed Anti‐Tachycardia Pacing Predicts Epicardial Ventricular Tachycardia Circuits in Patients With Non‐Ischemic Cardiomyopathy

Background Anti‐tachycardia pacing (ATP) that entrains but fails to terminate ventricular tachycardia (VT) provides an opportunity to use post‐pacing interval minus tachycardia cycle length (PPI − TCL) as a diagnostic tool. We evaluated whether PPI − TCL from failed ATP could predict the presence of epicardial re‐entrant VT circuits in patients with ischemic cardiomyopathies (ICM) vs. non‐ischemic cardiomyopathies (NICM). Methods A retrospective analysis was conducted of 51 patients who underwent VT ablation at Beth Israel Deaconess Medical Center from January 2020 to March 2025 and had failed ATP episodes recorded by their implantable cardioverter‐defibrillators (ICDs). PPI − TCL measurements and critical VT circuit locations (apex, septum, free wall, epicardial) were independently adjudicated. PPI − TCL was stratified by VT location and cardiomyopathy type, with sensitivity analyses for normalized PPI − TCL [(PPI − TCL)/TCL]. Results Included patients had a median age of 70 years, a median LVEF of 31%, 31 (61%) were infarct cardiomyopathy (ICM) and 20 (39%) were non‐infarct cardiomyopathies (NICM). ATP‐PPI was significantly longer at locations further from the ICD pacing electrode (i.e: free wall, epicardial) as compared to locations that were closer (i.e: apex, septum) ( p = 0.023). This relationship held true for NICM ( p = 0.026) but not for ICM ( p = 0.085). For patients with non‐infarct cardiomyopathies, an optimal ATP‐PPI cutoff of 165 ms provided an 86% sensitivity and 77% specificity for predicting epicardial circuits. Conclusion PPI − TCL following failed ATP reliably predicts epicardial VT circuits in NICM with a 165 ms cutoff offering high sensitivity and specificity. This non‐invasive tool may guide epicardial access planning in NICM VT ablation, though prospective validation is needed.