Clinical assessment and comparison of annotation algorithms in high-density mapping of regular atrial tachycardias

Background: High-density automated mapping of regular atrial tachycardias (ATs) requires accurate assessment of local activation times (LATs). Objective: To evaluate high-density mapping of ATs and compare the accuracy of different automated LAT annotation algorithms. Methods: Fifteen patients underwent AT ablation guided by the automated ConfiDENSE high-density mapping module (Carto 3 v4) allowing manual reannotation (edited maps). For each AT, unedited automated maps were reconstructed offline by three algorithms: maximum unipolar slope (LAT(Slope)), bipolar peak (LAT(Peak)), and a new hybrid annotation algorithm (LAT(Hybrid)). Five blinded experts were asked to define the (1) tachycardia mechanism, (2) ablation target, and (3) level of difficulty of these unedited maps. Results: Twenty-one ATs (cycle length 300 +/- 46 ms, activation points 955 +/- 421) were successfully ablated using LAT(Hybrid) guided ablation with manual editing in a small number of points. At 6 months, 14 (93%) of the patients were free of AT recurrences. Unedited LAT(Hybrid) maps showed the highest accuracy in defining the tachycardia mechanism (LAT(Hybrid): 49% vs. LAT(Peak): 27% vs. LAT(slope): 28%, P < 0,001) and ablation target (LAT(Hybrid): 65% vs. LAT(Peak): 39% vs. LAT(slope): 31%, P < 0.001). Overall, LAT(Hybrid)-annotated maps were graded as easier to interpret by the experts (difficulty score 2.3 +/- 0.9) versus LAT(Peak)(2.8 +/- 1) and LAT(slope)(3.2 +/- 0.8) (P< 0.001), Only 12% of the LAT(Hybrid) maps were annotated as uninterpretable compared to 31% of LAT(stope) and 45% of the LAT(Peak) maps (P < 0.001). Conclusion: Automated LAT(Hybrid) annotation allows better and easier recognition of the tachycardia mechanism compared to automated LAT(Peak) and LAT(stope) algorithms, although fully automated mapping still requires further improvements.