Novel Algorithmic Methods in Mapping of Atrial and Ventricular Tachycardia

Background— Conventional methods to assess local activation time (LAT) detect the peak of the bipolar electrogram (B-LAT Peak ) or the maximal negative slope of the unipolar electrogram (U-LAT Slope ). We evaluated 3 novel methods to assess LAT: onset (B-LAT Onset ) and center of mass (B-LAT CoM ) of bipolar electrogram, and maximal negative slope of unipolar electrogram within a predefined bipolar window (U-LAT Slope-hybrid ). Methods and Results— In 1753 atrial tachycardia and 1426 ventricular tachycardia recordings, the performance of the methods in detecting LAT was evaluated pair-wise (eg, B-LAT Peak versus B-LAT Onset ). For each comparison, histogram analysis of the differences in LAT values was performed. Variation in differences (P95-P5) in low quality (LQ) was compared with high-quality electrograms. In a separate data set (12 atrial tachycardia and 10 ventricular tachycardia), we evaluated for each method the accuracy in algorithmic activation mapping. Both in atrial tachycardia and ventricular tachycardia, the variation in difference between the conventional and novel methods was larger in LQ electrograms. In contrast, variation in difference between the novel methods was comparable in LQ and high-quality electrograms. Except for LAT Slope-hybrid , all methods showed decreased mapping accuracy with increasing percentage of LQ electrograms. U-LAT Slope-hybrid accurately mapped activation in 16 out of 22 maps (versus B-LAT CoM , 14; B-LAT Peak , 14; B-LAT Onset , 13; U-LAT Slope , 4). Conclusions— In LQ atrial and ventricular electrograms, the novel LAT methods (B-LAT Onset , B-LAT CoM , and U-LAT Slope-hybrid ) show less variation than the conventional methods. The U-LAT Slope-hybrid , a hybrid method that accurately detects the maximal negative unipolar slope, is associated with the highest accuracy in algorithmic mapping of atrial tachycardia/ventricular tachycardia.