Optimal Local Impedance Parameters for Catheter Ablation of the Cavo-tricuspid Isthmus in Atrial Flutter Patients: A...

Atrial flutter is a common arrhythmia, and catheter ablation offers a potentially curative intervention. However, there is a continued desire to enhance the procedure's efficiency and safety to optimize patient outcomes. Recently, local impedance (LI) has garnered attention as a novel approach to optimizing ablation procedures. The parameters of LI change when associated with durable ablation lesions for cavo-tricuspid isthmus (CTI) which remains poorly defined. This study aims to address this gap through analysis of gathered data.

We conducted a retrospective data analysis of 121 consecutive patients who underwent local impedance-guided catheter ablation of the CTI for typical atrial flutter. The durability of the ablated lesions was assessed using high-resolution activation and voltage mapping to detect conduction gaps. The maximum LI drop was calculated for each ablation point. Each point was assessed by 3-dimensional electroanatomic mapping with binary categorization denoting either durable/successful ablation lesion or non-durable/unsuccessful ablation lesion. In addition, subjective evaluation of catheter-tissue contact was assessed by a single proceduralist using intracardiac echocardiography (ICE) and was then stratified as high-level contact, intermediate-level contact, and low-level contact. A total of 1814 ablation points were analyzed.

The mean maximum drop in LI was significantly different (P < .0001) between the -16.38 ohms (95% confidence interval [CI], -17.54 to -15.23) for unsuccessful lesions and -20.79 ohms (95% CI, -21.20 to -20.38) for successful lesions. Among patients with at least 1 unsuccessful lesion, the maximum drop in LI was -16.38 for those that were unsuccessful in comparison to -19.81 for successful lesions (95% CI [-20.56, -19.06], P < .0001). The mean maximum drop in LI was progressively smaller moving from the high-level contact group (-25.93 ± 9.35), to the intermediate-level contact group (-19.04 ± 7.64), and again for the low-level contact group (-13.84 ± 6.93).

Our results give insight into the relationship between maximal local impedance change and the achievement of a durable block along the CTI.