Objective Spike and fragmented potentials have been documented in electrograms recorded at successful ablation sites in patients undergoing ablation for idiopathic ventricular arrhythmias from the aortic sinus cusp (ASC-IVAs) clinically. The aim of this study was to investigate the significance of these abnormal potentials in predicting target site of ASC-IVAs.

Methods Twenty-nine Patients with ASC-IVAs and ten control subjects were studied. Electroanatomical mapping was performed in RVOT and ASC during IVAs/sinus rhythm. The presystolic potential preceding the QRS complex during VAs were considered as pre-potential (PP), and late potential (LP) were fragment potential following the QRS complex during sinus rhythm before and after ablation. The characteristics of both of them were analysed between IVAs group and control group.

Results The incidence of PP and LP, the interval between QRS and LP and the amplitude of PP and LP in IVAs group were significantly greater than those of controls (P < 0.05). In IVAs groups, the amplitude of PP at the target site was smaller than that of unsuccessful site (0.240 ± 0.249 mV vs 0.798 ± 0.532mV, P = 0.004). LP was more often recorded at the target site than at an unsuccessful ablation site before and after RF application (before, P = 0.001; after, P < 0.001). After ablation, the amplitude of LP was obviously decreased (P = 0.016) and the interval between QRS and LP was longer in 21 patients (117 ± 28 ms vs 138 ± 31 ms P = 0.026) at the target site.

Conclusions Although many patterns of abnormal potentials were recorded at the target site during ablation of ASC-IVAs, LP has greater significance for guiding ablation. The increased interval between QRS and LP might become a sensitive and specific maker for predicting successful ablation.