Background  It is very difficult to locate ventricular arrhythmias of the tricuspid annulus (TA-VAs) by surface electrocardiogram (ECG), especially the accurate origin of TA-VAs.

Objective To summarize the surface ECG characteristics of TA-VAs, propose a method for locating TA-VAs using surface ECG, and verify it in clinical cases.

Methods Patients with TA-VAs who underwent RFCA guided by Carto 3 three-dimensional mapping system in the First Medical Center of Chinese PLA General Hospital from October 2013 to August 2023 were selected. With August 2021 as the boundary, they were divided into review group and validation group. The ECG data of patients were collected and analyzed, and an ECG algorithm was developed to identify TA-VAs originating from different directions. For VAs considering the origin of TA, the origin position could be located according to the QRS complex morphology of inferior leads and lead V1. For the patients in the review group, the above algorithm was applied to calculate the position of the origin point and compared with the actual ablation position, and the error between the calculated position and the actual ablation position was assessed to evaluate the accuracy of the method; For the patients in the verification group, the ECG algorithm was prospectively applied to predict the position of the origin point, and the ablation was preferentially mapped in the predicted direction of 1 o'clock. If the ablation was successful in this area, the ECG algorithm was considered to be successful.

Results A total of 88 patients were included and there were 62 cases in the review group, including 31 males and 31 females, with a median age of 54.00 (IQR: 35.00-64.25) years, and 26 cases in the validation group, including 17 males and 9 females, with a median age of 55.50 (IQR: 39.75-66.00) years. In this study, an ECG algorithm was developed to identify TA-VAs originating in different directions. For VAs considering TA origin, the location of origin could be located based on the combined application of QRS morphology in inferior leads and lead V1. The accuracy of this method in determining the orientation of the origin point of TA-VAs was 85% in the review group and 88% in the validation group, and the total accuracy was 86% in this study. The ablation time (216.68 ± 99.08 s vs 136.81 ± 68.89 s, P＜0.001) and operation time (99.82 ± 36.87 min vs 69.96 ± 30.51 min, P＜0.001) of the validation group were significantly shorter than those of the review group.

Conclusion TA-VAs has typical ECG features. More accurate localization of TA-VAs can be achieved by combining the ECG algorithm of inferior leads and lead V1 QRS morphology. TA-VAs ablation guided by the ECG algorithm in this study can shorten the operation time, reduce ineffective ablation, and improve the efficiency of the operation.