LVA mapping and analysis
After external cardioversion, a detailed bipolar LA voltage map was constructed during pacing from the distal CS in all patients. The LVA mapping method has been described previously.5,6,7 The mapping points were systematically acquired with the HDG, which has 16 electrodes and 3 mm equidistant electrode spacing to create a high density contact voltage map via the Ensite Velocity 3D mapping system. The algorithm displays the signals amalgamated from orthogonal recordings of each bipole and displays the highest amplitude signal (HD wave solution). An interpolation threshold of 10 mm on the NavX system was used for the surface color projection. Adequate endocardial contact was evaluated by stable electrograms and consideration of the distance to the geometry surface. Only true sinus beats were selected. Bipolar electrograms were filtered by a bandpass of frequencies between 30 and 500Hz. In accordance with the previous studies 5,6,7, an LVA was defined as an area with a bipolar peak-to-peak electrogram amplitude of <0.5mV and electrical scar areas as <0.1mV. The LA surface area was defined as the LA body area without the PV antrum regions inside the PVI line. The registration for evaluating the MDCT image with the NavX map consisted of an AF image imported (pre-ablation) with a post cardioversion SR map in all patients in order to obtain the anatomical information, and the overlap between the LVAs and high-DF sites was evaluated manually by 2 independent blinded observers.