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

## TL;DR

This study compares automated and manual methods for identifying heart activation sites during ablation procedures, finding significant differences depending on the origin of the heartbeats.

## Contribution

The study reveals that automated annotation methods can produce spatially discordant activation sites compared to manual methods, especially for certain heart regions.

## Key findings

- Automated annotation shows larger spatial differences in aortic sinus cusp-origin VPCs compared to other regions.
- Ventricular premature contractions from the right ventricular outflow tract septum and aortomitral continuity show moderate spatial discrepancies.
- The smallest spatial differences were observed in VPCs from the right ventricular outflow tract free wall.

## Abstract

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.

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.

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.

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).

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.