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Voltage Criteria for Left Atrial Scar Background Criteria have not been established for identifying LA scar using electroanatomic mapping (EAM). It is also unclear if voltage criteria using EAM may assist in identifying areas of pulmonary vein (PV) reconnection in patients undergoing repeat AF ablation. Objectives To characterize left atrial (LA) voltage in patients undergoing atrial fibrillation (AF) ablation. Methods An LA shell was created and bipolar voltage amplitude (in mV) at each point was measured. The shell was divided into 8 regions. Bipolar voltage values lower than the amplitude of 95% of sampled points was used as the upper cutoff value. Delayed enhancement (DE) cardiac magnetic resonance imaging (CMRI) sequences were performed to validate voltage cutoffs. Results Twenty patients participated. A mean of 141 ± 12 points constituted the LA map that was created during sinus rhythm (SR). In patients undergoing initial AF ablation, mean bipolar LA voltage was 1.44 ± 1.27 mV. In patients undergoing repeat AF ablation, scar along the posterior wall and LA-PV junction was identified using a voltage cutoff <0.2 mV, whereas a cutoff <0.45 mV best identified scar at other locations. This voltage range (0.2-0.45 mV) was useful to identify areas of reconnection around the PVs. On DE CMRI, a bipolar voltage cutoff of 0.27 mV performed best for delineating scar (sensitivity: 90%, specificity: 83%). Conclusions In patients undergoing AF ablation, EAM derived LA bipolar voltage shows regional variation. For maps acquired during SR, a voltage range of 0.2-0.45 mV can accurately demarcate LA scar distribution. This can be helpful in identifying PV reconnection in patients undergoing repeat AF ablation. [ABSTRACT FROM AUTHOR]

Unipolar Voltage Mapping in ICM Introduction Following myocardial infarction (MI), left ventricular function is determined by cardiac remodeling occurring in both infarcted and noninfarcted myocardium (NIM). Unipolar voltage mapping may detect remodeling changes in NIM that are associated with the left ventricular ejection fraction (LVEF). We aimed to identify (1) unipolar voltage characteristics in patients with chronic MI, and (2) association of voltage abnormalities with degree of left ventricular dysfunction (LVD). Methods and Results Two groups of patients with ischemic cardiomyopathy (ICM) who underwent LV endocardial mapping during catheter ablation for ventricular tachycardia (VT) between January 2010 and December 2012 were studied. The first group (19 males) had mild to moderate LVD (M-LVD, LVEF >35%) and was matched for age, sex, infarction size, and infarction location with 10 males who had severe LVD (S-LVD, LVEF <35%). Both bipolar and unipolar endocardial abnormal voltage areas were measured and compared between groups. Abnormal bipolar area was comparable in both groups (30 ± 8% in the S-LVD group vs 28 ± 8% in the M-LVD group; P = 0.5). Total abnormal unipolar voltage area was significantly larger in the S-LVD group (57 ± 14% vs 43 ± 13%; P = 0.02). The abnormal unipolar voltage area within the normal bipolar voltage area was greater in the S-LVD group (26 ± 11% vs 15 ± 16%; P = 0.03). In receiver operating characteristic curve analysis, an 18.0% cut-off value for abnormal unipolar area within NIM identified severe LVD, with 90% sensitivity and 79% specificity (area under the curve 0.821). Conclusions Patients with ICM and severe LVD have larger areas of unipolar voltage abnormality in the noninfarcted tissue than patients with M-LVD. [ABSTRACT FROM AUTHOR]