ResearchPod Summary
Can a deep learning framework combine temporal electrogram signal analysis with spatial graph representations to accurately characterise underlying cardiac tissue properties from spatially sparse, noisy intracardiac measurements?
To evaluate tissue characterisation without relying on intraprocedural arrhythmia episodes, the researchers generated synthetic electrogram (EGM) signals by solving the isotropic Aliev-Panfilov monodomain model on 2D flat squares and curved ellipsoid surfaces. They introduced three types of focal pathologies: fibrosis (via reduced diffusion coefficients), rapid depolarisation (via altered kinetics), and high excitability (via a negative excitation threshold).
The proposed high-resolution framework couples a temporal encoder module (a 1D convolutional neural network that compresses individual EGM traces into latent embeddings) with a spatial module (a graph neural network using graph attention layers). The graph represents sparse electrode nodes and dense tissue nodes, allowing information to be propagated across spatial neighborhoods. The model was trained on flat surfaces and tested on its ability to localize pathologies under conditions of electrode sparsity and noise, as well as its zero-shot and few-shot generalisation to curved geometries.
On 2D flat surfaces, the graph neural network framework substantially outperformed a baseline low-resolution CNN-only approach, achieving average precisions of 0.96 for single-patch fibrosis, 0.97 for rapid depolarisation, and 0.95 for high excitability. The high-resolution model also demonstrated strong robustness against electrode sparsity, maintaining reliable performance even when half of the electrodes were masked.
When transferred to curved surfaces in a zero-shot setting, the model successfully identified fibrosis and rapid depolarisation but struggled with high excitability. However, few-shot fine-tuning using just 10 curved surface simulations restored exceptional performance across all pathology types, yielding average precisions above 0.97 and highlighting the framework's strong generalisation potential.
By localizing pathological tissue substrates from sparse measurements during normal sinus rhythm, this approach could help clinicians plan ablation targets for premature ventricular complexes even when arrhythmias are infrequent or non-inducible during procedures, significantly reducing procedural time and improving success rates.
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