@inproceedings{liu-etal-2025-knowledge,
    title = "Knowledge-enhanced Multimodal {ECG} Representation Learning with Arbitrary-Lead Inputs",
    author = "Liu, Che  and
      Ouyang, Cheng  and
      Wan, Zhongwei  and
      Wang, Haozhe  and
      Bai, Wenjia  and
      Arcucci, Rossella",
    editor = "Christodoulopoulos, Christos  and
      Chakraborty, Tanmoy  and
      Rose, Carolyn  and
      Peng, Violet",
    booktitle = "Findings of the Association for Computational Linguistics: EMNLP 2025",
    month = nov,
    year = "2025",
    address = "Suzhou, China",
    publisher = "Association for Computational Linguistics",
    url = "https://preview.aclanthology.org/author-page-yu-wang-polytechnic/2025.findings-emnlp.385/",
    doi = "10.18653/v1/2025.findings-emnlp.385",
    pages = "7298--7316",
    ISBN = "979-8-89176-335-7",
    abstract = "Recent advancements in multimodal representation learning for electrocardiogram (ECG) have moved onto learning representations by aligning ECG signals with their paired free-text reports. However, current methods often result in suboptimal alignment of ECG signals with their corresponding text reports, thereby limiting diagnostic accuracy. This is primarily due to the complexity and unstructured nature of medical language, which makes it challenging to effectively align ECG signals with the corresponding text reports. Additionally, these methods are unable to handle arbitrary combinations of ECG leads as inputs, which poses a challenge since 12-lead ECGs may not always be available in under-resourced clinical environments.In this work, we propose the **Knowledge-enhanced Multimodal ECG Representation Learning (K-MERL)** framework to address these challenges. K-MERL leverages large language models (LLMs) to extract structured knowledge from free-text reports, enhancing the effectiveness of ECG multimodal learning. Furthermore, we design a lead-aware ECG encoder to capture lead-specific spatial-temporal characteristics of 12-lead ECGs, with dynamic lead masking. This novel encoder allows our framework to handle arbitrary lead inputs, rather than being limited to a fixed set of full 12 leads, which existing methods necessitate.We evaluate K-MERL on six external ECG datasets and demonstrate its superior capability. K-MERL not only outperforms all existing methods in zero-shot classification and linear probing tasks using 12 leads, but also achieves state-of-the-art (SOTA) results in partial-lead settings, with an average improvement of **16{\%}** in AUC score on zero-shot classification compared to previous SOTA multimodal methods. All data and code will be released upon acceptance."
}