Role of left ventricular scar and Purkinje-like potentials during mapping and ablation of ventricular fibrillation in dilated cardiomyopathy.

Background: Purkinje-like potentials (PLPs) have been described as important contributors to initiation of ventricular fibrillation (VF) in patients with normal hearts, ischemic cardiomyopathy, and early after-myocardial infarction. Methods: Of the 11 consecutive patients with VF storm, nonischemic cardiomyopathy (68 ± 22 years, left ventricular ejection fraction 28 ± 8%) who were given antiarrhythmic drugs and/or heart failure management, five had recurrent VF and underwent electrophysiology study (EPS) and catheter ablation. Results: At EPS, frequent monomorphic premature ventricular contractions (PVC) and/or ventricular tachycardia did not occur. With isoproterenol, VF was induced in three patients, and sustained monomorphic PVCs were induced in one patient. Three-dimensional electroanatomical mapping using CARTO (Biosense-Webster Inc., Diamond Bar, CA) revealed posterior wall scar in four of the five patients. PLP in sinus rhythm were recorded around the scar border in these four patients, and radiofrequency ablation targeting PLP was successfully performed at these sites. The patient without PLP did not undergo ablation. During follow-up (12 ± 5 months), only the patient without PLP had four VF recurrences requiring implantable cardioverter-defibrillator (ICD) shocks. Conclusion: In patients with VF and dilated cardiomyopathy, left ventricular posterior wall scar in the vicinity of the mitral annulus seems to be a common finding. Targeting PLP along the scar border zone for ablation seems to efficiently prevent VF recurrence in these patients.