Validation of bidirectional cavotricuspid isthmus block using electrocardiographic imaging

Abstract

Abstract Background The validation of bidirectional cavotricuspid isthmus (CTI) block following catheter ablation for typical atrial flutter (AFL) involves endocavitary manoeuvres using multiple catheters. The diagnostic capacity of electrocardiographic imaging (ECGi) as a non-invasive tool to confirm bidirectional CTI block may simplify the procedure but its benefit has not been investigated so far. Purpose To evaluate the diagnostic capacities of a novel imageless ECGi system in detecting bidirectional CTI block during AFL catheter ablation. Methods A total of 34 patients were consecutively included in a prospective single-centre study. Atrial activation maps were derived from a novel imageless ECGi system when pacing the septal and lateral aspects of the CTI, gauging the technology's capacities to detect bidirectional block by measuring transisthmic intervals (TII) and observing wave-front collision patterns. TII reflects the time taken for electrical activation to cross the CTI during pacing and we measured both the absolute value and the increase relative to its baseline value. The bidirectional CTI block was assessed by endocavitary manoeuvres using a multipole catheter as the gold-standard. We conducted a blind assessment of the diagnostic capacities of ECGi over endocavitary manoeuvres considering maps from the septal and lateral pacing to determine clockwise and counterclockwise CTI block, respectively. Results Our study established clear benchmarks for diagnosing CTI block using ECGi (Figure 1). Regarding the assessment of clockwise CTI block, the presence of a wave-front collision pattern at the CTI yielded a positive predictive value (PPV) of 91% and negative predictive value (NPV) of 69%. Furthermore, ROC analysis pinpointed 100 ms and 30 ms as the optimal threshold for TII absolute value (PPV=89%, NPV =78%) and TII increase from baseline (PPV=91%, NPV =65%), respectively. Taking together, the combination of these three parameters offered high diagnostic capacities (PPV=87%, NPV=90%). Regarding counterclockwise CTI block, the TII absolute value alone was a reliable predictor, with a threshold derived from ROC analysis of 115 ms providing a PPV of 77% and a NPV of 83% (Graphical abstract). Conclusion These results highlight the efficacy of ECGi in CTI block assessment, promising a streamlined and accurate diagnostic approach (Graphical abstract). The use of a single ablation catheter coupled with ECGi to assess the bidirectional CTI block offers a simplified and efficient alternative to traditional dual catheter techniques.ECGi-based CTI block assessment methodGraphical abstract