Background: Defining diastolic slow-conduction channels within the borderzone (BZ) of scar-dependent re-entrant ventricular tachycardia (VT) is key for effective mapping and ablation strategies. Understanding wavefront propagation is driving advances in high-density (HD) mapping. The newly developed Advisor™ HD Grid Mapping Catheter (HD GRID) has equidistant spacing of 16, 1 mm electrodes in a 4 × 4 3 mm interspaced arrangement allowing bipolar recordings along and uniquely across the splines (orthogonal vector) to facilitate substrate mapping in a WAVE configuration (WAVE). The purpose of this study was to determine the relative importance of the WAVE configuration compared to the STANDARD linear-only bipolar configuration (STANDARD) in defining VT substrate.
Methods: Thirteen patients underwent VT ablation at our institution. In all cases, a substrate map was constructed with the HD GRID in the WAVE configuration (conWAVE) to guide ablation strategy. At the end of the procedure, the voltage map was remapped in the STANDARD configuration (conSTANDARD) using the turbo-map function. Detailed post-hoc analysis of the WAVE and STANDARD maps was performed blinded to the configuration. Quantification of total scar area, BZ and dense scar area with assessment of conduction channels (CC) was performed.
Results: The substrate maps conSTANDARD vs conWAVE showed statistically significant differences in the total scar area (56 ± 32 cm2 vs 51 ± 30 cm2; p = 0.035), dense scar area (36 ± 25 cm2 vs 29 ± 22 cm2; p = 0.002) and number of CC (3.3 ± 1.6 vs 4.8 ± 2.5; p = 0.026). conWAVE collected more points than the conSTANDARD settings (p = 0.001); however, it used fewer points in map construction (p = 0.023).
Conclusions: The multipolar Advisor™ HD Grid Mapping Catheter in conWAVE provides more efficient point acquisition and greater VT substrate definition of the borderzone particularly at the low-voltage range compared to conSTANDARD. This greater resolution within the low-voltage range facilitated CC definition and quantification within the scar, which is essential in guiding the ablation strategy.
Keywords: Mapping catheters; Omnipolar high-density mapping catheter; Substrate ablation; Substrate mapping; Ventricular tachycardia.