Varying the ventricular activation wavefront during voltage mapping resulted in 22% and 14% variability in median bipolar and unipolar scar areas, with lower concordance in mixed versus dense scars.
Observational (n=29)
Does varying the ventricular activation wavefront alter myocardial scar characterization in patients with scar-related ventricular tachycardia?
Mapping with alternate activation wavefronts reveals significant variability in ventricular scar characterization, potentially improving the detection of arrhythmogenic substrates.
BACKGROUND: The effects of varying the wavefront of activation on ventricular scar characterization has not been systematically assessed. METHODS AND RESULTS: Patients referred for ablation of scar-related ventricular tachycardia underwent voltage maps during a minimum of 2 wavefronts of activation. The bipolar and unipolar low-voltage areas were compared, and direct electrogram analysis was performed in regions where discrepancies were seen. Concordance between wavefronts was measured by calculating percentage of overlap between maps. Sixty endocardial voltage maps (360±147 points) were performed in 29 patients during 2 distinct wavefronts, with 3 wavefronts in 7 patients. With median bipolar and unipolar low-voltage areas of 37 and 116 cm(2), respectively, 22% and 14% variability in median scar area was observed with a different activation wavefront. Concordance between wavefronts was lower in patients with mixed scar compared to those with dense scar (52% interquartile range, 29%-70% versus 84% interquartile range, 71%-87%), with septal scars exhibiting the lowest concordance (27% (interquartile range, 21%-56%). Among 16 critical sites for ventricular tachycardia, 3 (18%) were in a discordant region of scar, with one of the wavefronts showing voltage >1.5 mV. CONCLUSIONS: Significant differences in bipolar and unipolar low-voltage characterization of scar were observed with different ventricular activation wavefronts, particularly in septal locations and in patients without dense scar. In patients with a paucity of dense, low-voltage regions identified during substrate mapping, an alternate activation wavefront may increase the sensitivity to detect arrhythmogenic substrate and critical sites for ventricular tachycardia.
Tung et al. (2016) conducted an observational in Scar-related ventricular tachycardia (n=29). Voltage mapping during different wavefronts of activation vs. Alternate activation wavefronts was evaluated on Bipolar and unipolar low-voltage areas and concordance between wavefronts. Varying the ventricular activation wavefront during voltage mapping resulted in 22% and 14% variability in median bipolar and unipolar scar areas, with lower concordance in mixed versus dense scars.