Voltage mapping for delineating inexcitable dense scar in patients undergoing atrial fibrillation ablation: A new end point for enhancing pulmonary vein isolation

Background Characterization of left atrial scar using bipolar voltage (BiV) mapping is not well defined. We have previously shown that the BiV range of 0.2–0.45 mV can identify chronic scar from prior pulmonary vein isolation (PVI). Objective This study sought to determine a BiV range that can identify atrial inexcitable dense scar (IDS) in patients acutely and chronically after PVI. Methods Thirty consecutive patients undergoing first time (n = 15) or redo (n = 15) PVI were included. A left atrial shell was created using electroanatomic mapping, and IDS was defined by inability to capture at an output of 10 mA and a pulse width of 2 ms in sinus rhythm, circumferentially at the edge of PVI-related scar (≤5 mm). At each pacing site, BiV amplitude and atrial capture were recorded. Results Overall, 837 pacing sites were assessed. BiV predicted IDS (receiver operating characteristic curve area 0.93 for first time PVI and 0.90 for redo PVI). In first time PVI, the best BiV value to predict IDS was 0.45 mV for the left pulmonary vein–left atrial appendage (LAA-LPV) ridge (sensitivity 0.98; specificity 1.0) and 0.2 mV for other localizations (sensitivity 0.91; specificity 0.86). In redo PVI, the best BiV value to predict IDS was 0.2 mV for the LAA-LPV ridge (sensitivity 0.77; specificity 1.0) and 0.15 mV for other localizations (sensitivity 0.81; specificity 0.82). Conclusion BiV reproducibly identifies acute and chronic IDS using a cutoff value of 0.2 mV (0.45 mV for the LAA-LPV ridge) in patients undergoing first time PVI and 0.15 mV (0.2 mV for the LAA-LPV ridge) in patients undergoing redo PVI. IDS thus identified may be a rigorous tool for validating PVI.