Case 3:
A 63 year-old woman with apical hypertrophic cardiomyopathy (HCM) presented with nearly incessant VT at 115 bpm (RBBB superior axis) that failed to respond to beta blockers, amiodarone and mexiletine. VT was controlled with lidocaine that was stopped six hours prior to the study and she arrived in the EP laboratory in sinus rhythm. PES from the RVa with up to 3 extra stimuli down to refractoriness following a drive cycle length of 600 ms failed to induce VT. Polymorphic VT was induced with 400ms drive cycle length and two extra stimuli requiring external defibrillation. A substrate modification approach was planned and access to the LV was obtained by transseptal puncture. Burst pacing from the rim of the LV apical aneurysm at a cycle lengths of 300 ms readily induced the previously observed VT (Figure 3, panel A). Entrainment mapping was consistent with an isthmus at the lateral border of the aneurysm where the VT was successfully terminated (Figure 3, panel B). VT was no longer inducible following endocardial and epicardial ablation targeting the isthmus region.