Use of Stored Implanted Cardiac Defibrillator Electrograms in Catheter Ablation of Ventricular Fibrillation

BACKGROUND: Ventricular fibrillation (VF) can be abolished by targeting triggering ventricular ectopy, most often originating in the Purkinje network or right ventricular outflow tract (RVOT). This strategy relies upon the induction of premature ventricular complex (PVC) and/or VF. We sought to evaluate a VF ablation strategy that utilizes analysis of stored implantable cardioverter defibrillator (ICD) electrograms. METHODS: Eleven consecutive patients experiencing frequent VF episodes (≥three episodes in prior month) underwent electrophysiology study and ablation of VF triggers. PVC and VF induction was intentionally avoided or not possible in all of these patients. Pacemapping at likely sites for PVC triggers of VF using an analysis of the morphology and relative timing of the stored far- and near-field ICD electrograms of VF triggers was used to identify potential culprit locations. Radiofrequency energy was applied to these sites for ablation of the identified VF trigger. RESULTS: Areas targeted for ablation included the left posterior fascicle (six), left anterior fascicle (three), RVOT (three) and left ventricular outflow tract (one); two patients had two separate triggers. Ablation was completed successfully without any complications. With a mean follow-up of 288 days (range 45-649), 10 patients are free of VF. CONCLUSION: Ablation of VF triggers can be performed successfully with good short-term outcomes in patients with and without underlying heart disease. Use of stored ICD electrograms with a focus on likely target areas permit ablation without the need for PVC or VF induction. This can be useful when ectopy is not present for mapping and to avoid potentially dangerous initiation of multiple episodes of VF.