Differences Between the Unipolar Versus Bipolar Potential-Based Activation Maps of Ventricular Premature Contractions Arising From Ventricular Outflow Tracts

Abstract

Background

The use of an automated annotation algorithm based on the maximal negative derivative of the unipolar potential (−dV/dTmax) for local activation timing in the ablation of outflow tract (OT) ventricular premature contractions (VPCs) remains controversial.

Objective

To investigate the spatial differences in the earliest activation sites (EASs) of OT-VPCs identified by an automated annotation based on unipolar −dV/dTmax versus manual annotation using local bipolar potentials.

Methods

Seventy-nine patients with frequent OT-VPCs who underwent successful ablation were included. VPCs originated from the right ventricular OT (RVOT) free wall (n = 10), RVOT septum (n = 25), aortomitral continuity (AMC) (n = 19), and aortic sinus cusps (ASCs) (n = 25). The spatial distance between EASs identified by the two annotation methods was analyzed.

Results

The spatial distance between EASs was significantly larger in ASC-origin VPCs compared to non-ASC-origin VPCs (median: 11.9 mm [IQR: 7.9–14.9] vs. 1.2 mm [IQR: 0.0–3.3], p < 0.001). Among non-ASC-origin VPCs, the spatial difference was smallest in VPCs from the RVOT free wall (median: 0 mm) and larger in those from the RVOT septum (median: 1.6 mm) and AMC (median: 2.2 mm).

Conclusion

The spatial discordance of EAS between unipolar and bipolar mapping varies by the VPC origin site. The discrepancy is particularly pronounced in ASC-origin VPCs, emphasizing the need for careful interpretation of automated annotation algorithms to ensure accurate localization and effective ablation.