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Domain-Adapted Fine-Tuning of ECG Foundation Models for Multi-Label Structural Heart Disease Screening
Proceedings of the The 39th Canadian Conference on Artificial Intelligence, PMLR 318:678-692, 2026.
Abstract
Transthoracic echocardiography is the reference standard for confirming structural heart disease (SHD), but its use as a first-line screening modality is limited by cost, workflow burden, and specialist availability. This study investigated whether open pretrained electrocardiogram (ECG) models can support echo-confirmed multi-label SHD detection using the public EchoNext Mini-Model benchmark. We focused on six moderate-or-greater echocardiography-derived abnormalities spanning reduced left ventricular ejection fraction, increased left ventricular wall thickness, aortic stenosis, mitral regurgitation, tricuspid regurgitation, and right ventricular systolic dysfunction. Under a common experimental pipeline, we compared engineered ECG features with gradient boosting, end-to-end waveform learning from scratch, and transfer from open ECG foundation models. We then evaluated continued in-domain self-supervised adaptation of ECG-FM on EchoNext waveforms followed by selective supervised fine-tuning, with emphasis on the trade-off between discrimination and adaptation cost. Among the evaluated configurations, the adapted ECG-FM models achieved the strongest overall performance. Across adaptation depths, peak macro-AUROC and macro-AUPRC reached 0.8509 and 0.4297, respectively, while a more parameter-efficient operating point preserved nearly identical AUROC (0.8501) and achieved the highest fixed-threshold macro-F1 (0.3691). Late fusion of the release-provided covariates did not improve threshold-independent discrimination, and the evaluated low-rank adaptation (LoRA) configuration, alternative foundation backbones, and mixture-of-foundation-model strategies did not surpass the best adapted single-backbone operating points. These findings indicate that, for ECG-based case finding and echocardiography triage, the most effective transfer strategy is to combine target-domain self-supervised adaptation with selective supervised updating of a pretrained ECG backbone.