Clin Res Cardiol (2021) DOI DOI https://doi.org/10.1007/s00392-021-01843-w

Prospective Validation of a Stepwise Ultra-High-Density Mapping Approach for Critical Isthmus Identification in Atrial Tachycardia

N. Klatt1, J. Dickow2, L. Merbold2, A.-K. Kahle2, F. Moser2, B. Schäffer2, R. Ö. Akbulak3, P. Münkler2, L. Dinshaw2, R. Schleberger2, J. Hartmann3, M. A. Gunawardene3, M. Jularic3, C. Eickholt3, A. Metzner2, S. Willems3, C. Meyer4

1Klink für Innere Medizin und Kardiologie, Schön Klinik Neustadt, Neustadt in Holstein; 2Klinik und Poliklinik für Kardiologie, Universitäres Herz- und Gefäßzentrum Hamburg GmbH, Hamburg; 3Kardiologie, Asklepios Klinik St. Georg, Hamburg; 4Klinik für Kardiologie, Evangelisches Krankenhaus Düsseldorf, Düsseldorf;

Background: Identifying the critical isthmus in reentrant atrial tachycardia (AT) can be complex and conventional mapping methods are not always sufficient. Here we report the prospective validation of a stepwise ultra-high-density mapping approach for critical isthmus identification in AT. Methods: Using software tools for automated electrogram annotation and visualization of simultaneously activated atrial surface, 66 ATs from 60 patients were retrospectively analyzed to develop a stepwise mapping approach (derivation group): 1) Automated identification and highlighting of the least amount of simultaneously activated atrial surface during a full AT cycle length, depicted as a valley in the activation graph. 2) Exclusion of activation wave front dead ends. 3) Pinpointing the critical isthmus region by highlighting only potentials with high fractionation. This stepwise mapping approach was prospectively validated in 34 consecutive patients with 40 ATs, primarily only targeting the critical isthmus for ablation (validation group). Results: In the validation group (age 71.5 [56.0-77.5] years, 61.8% male, 79.4% consecutive ATs following catheter ablation of atrial fibrillation, LA volume 144.7±40.5 ml), by following the stepwise mapping approach, the critical isthmus was identified in 90.0% (36/40). Implementing our developed stepwise mapping approach in the validation cohort revealed one valley in 27/40 (67.5%), two valleys in 6/40 (15.0%), three valleys in 5/40 (12.5%) and more than three valleys in 2/40 (5.0%) ATs. The critical isthmus was highlighted in 75.0% (30/40) by the first valley, in 12.5% (5/40) by the second valley and in 2.5% (1/40) by the third valley; 10.0% (4/40) of critical isthmus were not highlighted by setting the window of interest to one of the valleys. Ablation strategy was based only on ablation of the critical isthmus site in 37.5% (15/40). In 62.5% (25/40), an ablation line covering the critical isthmus site and connecting it to adjacent low voltage areas was chosen. In 95.0% (34/34 initial ATs and 4/6 re-induced secondary ATs) ablation led to termination into sinus rhythm. Conclusion: Implementation of a novel stepwise mapping approach for HDM, addressing the amount of activated surface area in combination with the degree of fractionation, facilitates precise critical isthmus identification in patients with AT and enables a targeted ablation strategy. Targeted ablation of the critical isthmus site solely or in addition to conventional anatomical lines appears to be an effective approach for AT ablation with high acute success rates.

https://dgk.org/kongress_programme/jt2021/aP164.html