Late fractionated potentials in catheter ablation for right ventricular outflow tract ventricular arrhythmias

A simplified approach to radiofrequency catheter ablation of idiopathic ventricular outflow tract premature ventricular contractions

BACKGROUND

Frequently, low voltage areas (LVAs) and diastolic potentials (DPs) are present at ablation site in sinus rhythm in patients with idiopathic premature ventricular contractions (PVCs).

OBJECTIVE

Validate these findings as substrate for PVCs and evaluate the feasibility of a simplified substrate approach based on LVAs and DPs for ablation of idiopathic outflow tract PVCs, in patients with a low PVC burden during the procedure.

METHODS

Prospective single-arm clinical trial at two centers with comparison with a historical group, matched to age and gender. The study group consisted of consecutive patients referred for ablation of frequent idiopathic PVCs with inferior axis, that presented with less than 2 PVCs/min in first 5 minutes of the procedure. The ablation was based on fast mapping of the RVOT in sinus rhythm looking for LVAs and DPs, defined as isolated small amplitude potentials occurring after the T wave of the surface ECG. The area with LVAs and DPs was tagged, and a simplified activation mapping of the PVCs was done in that area. The procedure time, success rate and recurrence rate were compared with the historical group in whom ablation was performed based on activation and pace mapping only. A validation group without PVCs was also studied to assess the prevalence of LVAs and DPs in the general population.

RESULTS

The study (n=38), historical (n=38) and validation (n=38) groups did not differ in relation to age or gender. Prevalence of LVAs and DPs was significantly higher in the study group in comparison with the validation group, respectively, 71% vs 11%, p<0.0001 and 87% vs 8%, p<0.0001. Procedure time was significantly lower in the study group when comparing to the historical group, 130 (100-164) vs 183 (160-203) min, p<0.0001 and the success rate was significantly higher, 90% vs 64%, p=0.013. The recurrence rate in patients with a successful ablation was not significantly different between both groups, Log-Rank=0.125.

CONCLUSION

Prevalence of LVAs and DPs was significantly higher in the study group than in the validation group. The proposed approach proved to be feasible, faster and more efficient than the historical approach. This article is protected by copyright. All rights reserved.

Novel strategy of remote magnetic navigation-guided ablation for ventricular arrhythmias from right ventricle outflow tract

The optimized strategy to further increase the success rate of ablation for ventricular arrhythmias (VAs) from the right ventricular outflow tract (RVOT) is challenging. Recent studies have shown that the pulmonary sinus cusp (PSC) region may be the origin of certain RVOT VAs. We evaluated the efficacy of preferential ablation below the pulmonary valve (PV) and alternated radiofrequency delivery in the PSC using remote magnetic navigation (RMN). Sixty-five (65) consecutive patients experiencing VAs with RVOT-like appearance were included in this study. Mapping and ablation were preferentially performed below the PV. Ablation in the PSC would only be attempted when intensified ablation below the PV could not eliminate VAs. Finally, if ablation in the RVOT region failed, the aortic sinus cusp (ASC) would be mapped. Sixty-one (61) of 65 (93.8%) patients achieved procedural success. Except 7 cases of which the VAs were ablated in the ASC, the rest 54 VAs were thought to be originate from the RVOT region. Fifty (50) of 54 VAs were successfully ablated below the PV, and in the presence of a local special signal in the bipolar electrogram a more aggressive ablation was required. Subsequent ablation in the PSC with assistance of the RMN system achieved success in the remaining 4 patients. No complications occurred in this study. Our strategy of using RMN-guided ablation below the PV for VAs of RVOT origin was proved to be effective. PSC mapping and ablation using a magnetic catheter may provide the optimal strategy for treating these types of arrhythmias.