Case 4:
A 64 year old man with ischemic cardiomyopathy and recurrent VT despite amiodarone, mexiletine and two prior ablation procedures presented for repeat VT ablation. PES from the RV apex with up to three extrastimuli down to refractoriness or a minimum coupling interval of 180 ms at two drive cycle lengths (400 and 600 ms) did not induce VT. A substrate approach was planned and LV mapping revealed a large low voltage (< 1.5mV) inferior and lateral scar. PES from the septal border zone of the scar with up to two extrastimuli following a basic drive cycle length of 600 ms induced four different sustained monomorphic VTs with cycle lengths of 268ms to 566ms and QRS morphologies consistent with origin from the mid-lateral and mid-inferoseptal aspects of the infarct scar. Following ablation, VTs were no longer inducible with PES from either the RV or LV. NIPS two days after the procedure via the RV lead of the patient’s defibrillator did not induce VT.