Rapid mapping and differentiation in ventricular outflow tract arrhythmia using non-contact mapping

Ventricular outflow tract arrhythmias (VOTAs) can be successfully treated by catheter ablation. However, it is sometimes difficult to differentiate the origin of VOTAs between the right ventricular outflow tract (RVOT) and the other sites, leading to a long fluoroscopy time and unnecessary radiofrequency applications. This study aimed to clarify distinguishable characteristics of the propagation pattern obtained from non-contact mapping (NCM) for VOTA ablation.

Consecutive 45 patients with VOTAs who underwent catheter ablation using the NCM system were included in this study. We analyzed an isopotential map on three-dimensional geometry of the RVOT obtained from the virtual unipolar electrograms (VUEs) and assessed mapping data of the isopotential area with an initial negative VUE of -1 mV.

Successful ablation was achieved from the endocardial RVOT in 34 patients (RVOT group) and the non-RVOT in 11 (non-RVOT group). Major and minor axis diameters of the isopotential area did not significantly differ between the two groups. However, a ratio of major/minor axis diameter was greater in the RVOT group (1.9 ± 0.1 versus 1.3 ± 0.1; P < 0.001). In addition, the propagation velocity defined as an increase of the isopotential area per millisecond was significantly slower in the RVOT group (2.2 ± 0.4 versus 4.2 ± 0.7 mm²/ms; P = 0.02).

The isopotential area of VOTAs originating from the RVOT, as compared to the other sites, spread more elliptically and slowly. The propagation pattern obtained from NCM can provide useful information and efficient strategy for VOTA ablation.