Local ventricular activation at the distal great cardiac vein determines right- and left-sided approach for catheter ablation of outflow tract arrhythmias: a simple and rapid discriminator

Abstract Background When the precordial transition zone (TZ) of idiopathic outflow tract arrhythmias (OTAs) is present around lead V3, it may be difficult to precisely determine which outflow tract is responsible for the origin of the OTAs from the ECG characteristics. Purpose We hypothesized that mapping around the distal portion of the great cardiac vein (dGCV) would be useful for identifying which outflow tract is the origin of OTAs during radiofrequency catheter ablation (RFA). Methods Among 28 OTA patients who underwent dGCV mapping and successful RFA at our institution from June 2021 to February 2024, 16 whose TZ during the OTAs was ＞lead V2 and ＜lead V4 were included in this study. In all patients, activation mapping around the dGCV with the novel 2.7 Fr over-the-wire (OTW)-type decapolar catheter was performed during the OTAs. Results In all patients, the mapping catheter could be easily placed in the dGCV. In patients whose OTAs were successfully ablated from the left-sided OT (n=7), the local ventricular activation time in the dGCV during OTAs preceded the QRS onset (LAT-dGCV) by -26.1±7.0 msec, which was significantly earlier than that of OTAs successfully ablated from the right-sided OT (n=9; -4.0±5.7 msec; p<0.001). An LAT-dGCV >-18 msec indicated a left-sided OTA, and right-sided and left-sided OTAs were completely distinct. Patients with an LAT-dGCV >-18 msec and mapping initiated first in the left-sided OT had shorter procedure times than those with mapping initiated first in the right-sided OT (p<0.001). Conclusions Mapping the dGCV with this OTW-type catheter is easy and safe. The earliness of the local ventricular activation in the dGCV during OTAs could easily and precisely differentiate between right-sided and left-sided OTAs, resulting in a successful ablation with a shorter procedure time.