Comparison of high-density mapping of regular atrial tachyarrhythmia between an octaspline and a pentaspline multi-electrode catheter: a randomized cross-over trial

Ablation of reentrant atrial tachyarrhythmia (AT) remains challenging and time-consuming, even in the era of advanced mapping systems. Compared to the Pentaray catheter, the recently developed Octaray catheter has 3 additional splines and features a non-contact central electrode and more closely spaced electrodes, which potentially improves signal quality and increases mapping efficiency.

To investigate the efficiency and mapping quality of the Octaray (2-5-2-5-2 mm spacing) catheter compared to the Pentaray (2-6-2 mm spacing) catheter for mapping AT using the CARTO Coherent module.

Patients with either left- or right-atrium AT were included in this study to undergo 3D Coherent mapping with both catheters in a crossover design, with the mapping order determined by randomization. To ensure a fair comparison, only the 3D anatomy of the chamber of interest was initially created without displaying the activation map to the operator. Subsequently, an activation map was generated on this anatomical shell twice—once with each catheter—following CARTO best-practice settings. Mapping was considered complete when activation map filling threshold of 5 millimeters was achieved across the entire anatomical shell area. The primary endpoint was the total number of electrograms per map. A total of 18 patients were required to achieve 90% power to detect a difference of 250 electrograms; thus, the study was powered separately for left- and right-atrium AT.

A total of 46 patients with either left- or right-atrium AT were randomized across three ablation centers. Successful AT mapping was achieved in 39 patients using both catheters: 20 with left atrial scar-related macro-reentrant AT (atypical flutters) and 19 with right-atrium AT (68% typical flutters). In the 7 patients, AT stopped after randomization, either before starting the map or during mapping, and reinduction of AT was unsuccessful. The average number of electrograms per map was about 50% higher with the Octaray catheter (mean ± SD: 8,569 ± 4,880 vs. 5,689 ± 3,450 with the Pentaray; P<0.001), despite a shorter mean mapping time with the Octaray (5.7 ± 1.8 minutes vs. 8.6 ± 3.0 minutes with the Pentaray; P < 0.001). These differences were consistent in separate comparisons for the left and right atria. However, the mean electrogram acquisition rate (electrograms per minute) was higher in the left atrium as compared to the right atrium (mean difference: 1,211 vs. 644 electrograms/min, both favoring the Octaray), particularly in cases with extensive scarring, reflecting the Octaray catheter’s higher resolution and better ability to define scar and identify critical isthmus (Figure).

The Octaray catheter maps ATs significantly faster and with higher resolution than the Pentaray, which may be especially useful for complex macro-reentrant ATs. Quantifying signal quality differences will be part of further analyses on this dataset.