Role of notched unipolar electrogram in guiding catheter ablation of frequent premature ventricular contractions originating from the ventricular outflow tracts

Lihong Huang ,Yuxing Wang ,Xiandong Yin ,Yanjiang Wang ,Bo Xie ,Ying Tian ,Xiaoqing Liu ,Liang Shi ,Lijun Zeng ,Xinchun Yang

doi:10.3760/cma.j.issn.1007-6638.2018.05.002

Abstract

Objective The purpose of this study was to investigate the value of notched unipolar electrogram (N-uniEGM) in guiding radiofrequency ablation of premature ventricular contractions (PVC) originating from the ventricular outflow tract (VOT) . Methods In 190 consecutive patients with idiopathic frequent VOT-PVC, mapping and radiofrequency ablation were performed using the Carto3 system in Heart center of Beijing Chaoyang Hospital from May 2011 to December 2017. The average PVC-burden before the procedure was 20.4%±11.2%. The characteristic of unipolar electrogram at successful target was analyzed. N-uniEGM was defined as unipolar electrogram with a QS morphology and one or more notches in the downstroke deflection. Patients were divided into two groups, N-uniEGM positive group and negative group. The success rate, the valid ablation time and the total ablation time were compared between two groups. The sensitivity and the specificity of N-uniEGM in predicting successful ablation were also evaluated. Results N-uniEGM was recorded in 124/190 (65.3%) patients, including 97 right ventricular outflow tract (RVOT) PVC, 22 aortic cusps PVC and 5 subaortic valve PVC. In the majority of patients, the sites presenting with N-uniEGM also showed ideal activation mapping and pace mapping. The average area of the sites presenting with N-uniEGM was merely (0.8±0.4) cm2. The number of notches in N-uniEGM in RVOT, aortic cusps, and subaortic value were (1.2±0.5) , (1.4±0.8) and (1.7±0.6) , respectively. The success rate of PVC ablation in patients presenting with N-uniEGM was 98.4% (122/124) . The valid ablation time was significantly shorter in patients with N-uniEGM than in those without it[ (7.6±3.8) s vs. (15.8±8.8) s, P<0.05]. The difference was also observed in the total ablation time[ (178±36) s vs. (260±114) s, P<0.05]. The sensitivity and the specificity of N-uniEGM in predicting successful ablation of VOT-PVC was 72.6% and 91.7%, respectively. Conclusions N-uniEGM is a highly specific and moderate sensitive predictor of successful radiofrequency ablation for patients with VOT-PVC. Key words: Ventricular premature complexes; Heart ventricules; Catheter ablation; Unipolar mapping

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