Introduction

Identifying the critical isthmus of complex atrial tachycardia (AT) is challenging. The Lumipoint^® (LP) software tool developed for the Rhythmia® mapping system generates an electrical activation (EA) pattern over the AT cycle length (CL) providing a detailed cumulative EA related to the anatomical information at a certain time point. This feature aims to facilitate successful termination of atrial arrhythmias by identifying the critical isthmus region (CIR). 

Objective

Objective of this study was to characterize and analyze the EA pattern of ATs in detail with respect to potential prediction of the CIR in patients with atypical atrial flutter (AAF).

Methods

In this retrospective analysis we analyzed 57 atrial macro-reentry tachycardias, 49 left atrial and 8 right atrial. Electrical activity (EA) was mapped over the complete AT CL, obtaining a 2-dimensional EA pattern based on the hypothesis that low EA regions serve as surrogates of slow conduction.

Results

A total of n=33 patients were included into the analysis LP algorithm identified a mean number of 2.4 EA minima and 4.4 suggested CRIs per AAF form. Overall, the algorithm showed a low specificity with 12.3% but a high sensitivity of 98.2% (figure A). Further EA analysis revealed that the depth (lowest minima) and the width (widest minima) were the best predictors of the CIR of the AT with respect to sensitivity and specificity (Figure B and C). However, occurrence of wide minima were not frequent, while low minima were present in larger extent.  We observed that minima with depth of EA ≤20% showed the best sensitivity as well as specificity (95% and 60% respectively, figure D). Furthermore, we sought to evaluate if suggested CIR, not involved in the index AAF, were relevant for future clinical ATs. Repeat ablations in patients with recurrent AAF (n=9) revealed that the CIR of recurrent AAF was already detected by LP during the index ablation in 9 out of 9 cases.

Conclusion

The LP algorithm provides an excellent sensitivity (98.2%), but poor overall specificity (12.3%) to detect the CIR of the macro-reentry tachycardia based on our analysis. However, specificity improved significantly by preselection of the lowest EA minima. In addition, initial detected irrelevant bystander CIRs during the index procedure might become relevant for future AFFs potentially identifying an arrhythmogenic substrate.