# Electromechanical wave imaging vs electrocardiographic imaging: a direct comparison of non-invasive ventricular activation mapping modalities

## TL;DR

This study compares two non-invasive methods for mapping the origin of heart arrhythmias, finding that both have strengths and weaknesses in identifying the correct location.

## Contribution

The paper provides a direct comparison of EWI and ECGI for non-invasive ventricular activation mapping, highlighting their specific advantages and limitations.

## Key findings

- ECGI correctly identified the anatomical site of origin in 77.8% of cases, while EWI did so in 80%.
- EWI accurately determined transmural sites in 77.1% of cases, which ECGI could not reliably do.
- ECGI excels in mapping multifocal or infrequent arrhythmias due to its panoramic single-beat mapping capability.

## Abstract

Precise non-invasive identification of the site of origin (SoO) of ventricular arrhythmias (VA) could inform ablation strategies.

To compare spatial accuracy of ultrasound-based electromechanical wave imaging (EWI) and ECG imaging (ECGI) to estimate the anatomical and axial (endo- vs epicardial) SoO of focal VA or pace maps employing contact mapping as gold standard.

Patients awaiting a catheter ablation procedure underwent preprocedural EWI and ECGI to non-invasively map the SoO of VE/VT or RV and LV pacing sites. A commercial CT-ECGI system was used to reconstruct epicardial activation maps. Unipolar EGM morphology and slew rate were employed to estimate axial SoO. EWI was performed using high frame rate (2000fps) transthoracic echocardiography with simultaneous ECG. Contact mapping and pacing sites were used as gold standard to define SoOs.

Thirty-three patients with 36 maps in total were included, 24 patients for VE/VT activation and 9 for pace-mapping. ECGI correctly identified the segmental VA-SoO/pacing-site in 28/36 maps (77.8%) compared to 28/35 by EWI (80%, p = ns). Erroneous annotations in ECGI related to septal and papillary muscle foci, whereas EWI mostly misannotated in outflow tract and RV SoOs. One patient had insufficient VEs to allow EWI VA mapping. Reconstructed unipolar EGM features of ECGI maps did not reliably differentiate endo- from epicardial SoO. Direct transmural mapping with EWI correctly identified the “transmural” SoO in 27/35 (77.1%).

Both EWI and ECGI localized the anatomical SoO in the majority of cases with site-specific advantages but also shortcomings for both modalities. EWI determines the transmural SoO which cannot be reliably localized using ECGI. ECGI has the advantage of providing mapping of multifocal and/or infrequent VA by offering panoramic single beat mapping.

The online version contains supplementary material available at 10.1007/s10840-025-02156-y.