Background-Patients with nonischemic left ventricular cardiomyopathy (LVCM) and ventricular tachycardia (VT) havecomplex 3-dimensional substrate with variable involvement of the endocardium (ENDO) and epicardium (EPI). The purpose of this study was to determine whether ENDO unipolar (UNI) mapping with a larger electric field of view could identify EPI low bipolar (BIP) voltage regions in patients with LVCM undergoing VT ablation. Methods and Results-The reference value for normal ENDO unipolar voltage was determined from 6 patients without structural heart disease. Consecutive patients undergoing VT ablation over an 8-year period with detailed (Ͼ100 points) LV ENDO and EPI mapping and normal LV ENDO BIP voltage were identified. From this cohort, we compared patients with structurally normal hearts and normal EPI BIP voltage (EPIϪ, group 1) with patients with LVCM and low LV EPI BIP voltage regions present (EPIϩ, group 2). Confluent regions of ENDO UNI and EPI BIP low voltage (Ͼ2 cm 2 ) were measured. The normal signal amplitude was Ͼ8.27 mV for LV ENDO UNI electrograms. Detailed LV ENDO-EPI maps in 5 EPIϪ patients were compared with 11 EPIϩ patients. Confluent ENDO UNI low-voltage regions were seen in 9 of 11 (82%) of the EPIϩ (group 2) patients compared with none of 5 EPIϪ (group 1) patients (PϽ0.001). In all 9 patients with ENDO UNI low voltage, the ENDO UNI low-voltage regions were directly opposite to an area of EPI BIP low voltage (61% ENDO UNI-EPI BIP low-voltage area overlap). Conclusions-EPI arrhythmia substrate can be reliably identified in most patients with LVCM using ENDO UNI voltage mapping in the absence of ENDO BIP abnormalities. (Circ Arrhythm Electrophysiol. 2011;4:49-55.)

In patients with NICM and VT of epicardial origin, the substrate is characterized by areas of basal LV epicardial > endocardial bipolar low voltage. The electrograms in these areas are not only small (<1.0 mV) but wide (>80 ms), split, and/or late, and help identify the substrate targeted for successful ablation.

Background-The single-procedure efficacy of pulmonary vein isolation (PVI) is less than optimal in patients with persistent atrial fibrillation (AF). Adjunctive techniques have been developed to enhance single-procedure efficacy in these patients. We conducted a study to compare 3 ablation strategies in patients with persistent AF. Methods and Results-Subjects were randomized as follows: arm 1, PVI ϩ ablation of non-PV triggers identified using a stimulation protocol (standard approach); arm 2, standard approach ϩ empirical ablation at common non-PV AF trigger sites (mitral annulus, fossa ovalis, eustachian ridge, crista terminalis, and superior vena cava); or arm 3, standard approach ϩ ablation of left atrial complex fractionated electrogram sites. Patients were seen at 6 weeks, 6 months, and 1 year; transtelephonic monitoring was performed at each visit. Antiarrhythmic drugs were discontinued at 3 to 6 months. The primary study end point was freedom from atrial arrhythmias off antiarrhythmic drugs at 1 year after a single-ablation procedure. A total of 156 patients (aged 59Ϯ9 years; 136 males; AF duration, 47Ϯ50 months) participated (arm 1, 55 patients; arm 2, 50 patients; arm 3, 51 patients). Procedural outcomes (procedure, fluoroscopy, and PVI times) were comparable between the 3 arms. More lesions were required to target non-PV trigger sites than a complex fractionated electrogram (33Ϯ9 versus 22Ϯ9; PϽ0.001). The primary end point was achieved in 71 patients and was worse in arm 3 (29%) compared with arm 1 (49%; Pϭ0.04) and arm 2 (58%; Pϭ0.004). Conclusions-These

R adiofrequency catheter ablation (RFCA) has an established therapeutic role in managing recurrent drug-refractory scar-related ventricular tachycardia (VT). 1 Owing to the complex substrate, concomitant heart failure, and associated comorbidities, patients undergoing catheter ablation of scarrelated VT experience significant morbidity and mortality rates. 2,3 In these patients, use of anesthesia, sustained hypotension as a result of spontaneous or induced VT, and fluid overload might contribute to periprocedural acute hemodynamic decompensation (AHD) requiring advanced hemodynamic support or procedure discontinuation. 4,5 Thus far, no data are available on the prevalence, predictors, and clinical significance of periprocedural AHD during catheter ablation of scarrelated VT. The proper identification of patients at high risk of periprocedural AHD would also have important implications for procedural planning because it would allow anticipation of the need for mechanical hemodynamic support. In this study, we evaluated the incidence and clinical predictors of periprocedural AHD during RFCA of scar-related VT and assessed its effect on mortality. MethodsThe study cohort consisted of consecutive patients who underwent RFCA of scar-related VT in the setting of ischemic or nonischemic cardiomyopathy at the Hospital of the University of Pennsylvania between January 2010 and December 2011. Patients with idiopathic VT and those with congenital heart disease were excluded. Whenever possible, antiarrhythmic drugs were discontinued for ≥4 half-lives before the procedure. Patients who were on chronic therapy with β-blockers or inhibitors of the renin-angiotensin-aldosterone system routinely held the medications the morning of the procedure (last dose administered the night before). Before the procedure, all patients © 2014 American Heart Association, Inc. P=0.004). At 21±7 months follow-up, the mortality rate was higher in the AHD group compared with the rest of the population (50% versus 11%, log-rank P<0.001). Conclusions-AHD occurs in 11% of patients undergoing radiofrequency catheter ablation of scar-related VT and is associated with increased risk of mortality over follow-up. AHD may be predicted by clinical factors, including advanced age, ischemic cardiomyopathy, more severe heart failure status (New York Heart Association class III/IV, lower ejection fraction), associated comorbidities (diabetes mellitus and chronic obstructive pulmonary disease), presentation with VT storm, and use of general anesthesia. (Circ Arrhythm Electrophysiol. 2015;8:68-75.

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