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Figure 2 Electrogram Prevalence and Density

The right anterior oblique projections of the 2 patients from Figure 1 are shown in A with scar-related electrograms annotated as follows: fractionated potentials (FP) in light blue, isolated potentials (IP) in white, and very late potentials (VLP) in gray. In the SMVT patient at the bottom of the panel, FPs were found around the VLZ border; IP and VLP were found deeper inside the VLZ. In the control patient, there is an extreme paucity of scar-related electrograms despite high-density point sampling in the smaller low-voltage zone. The global prevalence of scar-related electrograms was significantly greater in the SMVT group as shown in B. Fundamental differences in the composition and potential arrhythmogenicity of the abnormal substrate are suggested by the data in C, where Group 2 has a higher density of FP and VLP per unit low-voltage zone area. Abbreviations as in Figure 1.