Empiric ablation of polymorphic ventricular tachycardia/fibrillation in the absence of a mappable trigger: Prospective feasibility and efficacy of pacemap matching to defibrillator electrograms

Heart Rhythm. 2022 Apr;19(4):527-535. doi: 10.1016/j.hrthm.2021.10.025. Epub 2021 Oct 30.


Background: Catheter ablation strategies for ventricular fibrillation (VF) and polymorphic ventricular tachycardia (PMVT) are not established when spontaneous triggers are rare or absent.

Objective: The purpose of this study was to report the feasibility and efficacy of a novel empiric ablation strategy of pacemapping to stored implantable cardioverter-defibrillator (ICD) template electrograms (SITE) of the clinical premature ventricular contraction (PVC) trigger.

Methods: Fifteen patients with drug-refractory VF/PMVT receiving defibrillator shocks without identifiable and mappable PVC triggers were prospectively analyzed. The protocol incorporated systematic pacemapping from known arrhythmogenic sites (moderator band/right ventricular [RV] papillary muscles, left conduction system/Purkinje network, outflow tracts) with real-time comparison between the paced ICD electrogram (EGM) morphology and SITE.

Results: Regions within the left Purkinje network yielded the best pacemap match for the SITE of the clinical PVC trigger in 55% of ablation targets (left posterior fascicle 6, left septal fascicle 1, left anterior fascicle 5), followed by the RV moderator band region in 14% (n = 3), RV papillary muscles in 13% (n = 3), periaortic region in 14% (n = 3), and left ventricular anterolateral papillary muscle in 4% (n = 1). Freedom from ICD therapies off antiarrhythmic drug (AAD) was 64% at 6 months and 48% at 12 months. Shock burden was reduced from 4 (2-6) to 0 (0-1) (P = .001), and use of AADs was reduced from 2 (1-2) to 0 (0-1) (P = .001).

Conclusion: In the absence of a mappable trigger, an empiric strategy of interrogating the Purkinje network, papillary muscles, and outflow tract regions by pacemap matching with SITE of the clinical PVC is feasible to guide ablation. A significant reduction in VF/PMVT therapy burden and AAD utilization was observed after a single procedure.

Keywords: Ablation; Pacemap; Polymorphic tachycardia; Premature ventricular contraction; Ventricular fibrillation; Ventricular tachycardia.

MeSH terms

  • Catheter Ablation* / methods
  • Defibrillators, Implantable*
  • Feasibility Studies
  • Humans
  • Prospective Studies
  • Tachycardia, Ventricular* / surgery
  • Ventricular Fibrillation
  • Ventricular Premature Complexes*