Ablation of epicardial ventricular arrhythmias from nonepicardial sites

BackgroundIdiopathic epicardial ventricular arrhythmias can be targeted from the coronary venous system or the pericardial space, the endocardium, or the aortic sinus cusps.ObjectiveThe purpose of this study was to analyze systematically the contribution of ablation at sites other than the epicardium to eliminate an arrhythmia originating in the epicardium.MethodsIn a consecutive patient series of 33 patients (14 women, age 51 ± 14 years, ejection fraction 51% ± 9%) with epicardial ventricular arrhythmias, mapping and ablation was performed via the cardiac venous system/pericardial space, the aortic sinus cusp, and the left ventricular endocardium. An arrhythmia was defined as epicardial if the earliest onset of activation and a matching pace-map (≥10/12 leads) were identified in the epicardium.ResultsIn 12/33 patients (36%), either an endocardial approach alone (n = 3) or a combined endocardial/epicardial (n = 6), cusp/endocardial (n = 1), or cusp/epicardial (n = 2) approach was required to eliminate the ventricular arrhythmias. In 10 of 33 patients (30%), epicardial ablation alone was effective in eliminating epicardial ventricular arrhythmias. Ablation was ineffective due to failure to reach the site of origin with the ablation catheter in 5 of 33 patients (15%), the site of origin was too close to an epicardial artery or the phrenic nerve in 3 patients (6%), and power delivery was insufficient in 3 patients (9%).ConclusionAbout one-third of epicardial arrhythmias require ablation from sites other than the epicardium to eliminate the arrhythmia focus.