Beyond Black Boxes: Multi-Domain Soft Set Framework for Explainable ECG Arrhythmia Detection

Electrocardiogram (ECG) arrhythmia classification remains critical for early heart disease detection, but current deep learning approaches sacrifice interpretability for performance gains. This limitation poses obstacles to clinical application. To address this challenge, a multi-domain soft set framework was introduced and achieved 96.9\% accuracy using only 35 interpretable features on the MIT-BIH Arrhythmia Database. Four machine learning classifiers (Random Forest, XGBoost, LightGBM, SVM) were systematically compared via 5-fold cross-validation, with LightGBM selected to provide the optimal balance between accuracy (96.9\%), computational efficiency (approximately 9 seconds per fold), and stability. To assess generalizability, cross-database validation was further conducted on the St. Petersburg INCART 12-lead Arrhythmia Database using the identical framework and parameter configuration, with all four classifiers achieving accuracies exceeding 96\%.Through extensive ablation studies, soft set features were shown to contribute an absolute improvement of 7.7\% over baseline statistical features (89.2\% vs. 96.9\%). SHAP explainability analysis confirmed the physiological interpretability of the framework, revealing that temporal dynamics (TDSS-thresh: 60.6\% significance) and frequency features (FTSS-std: 52.9\%) were the most discriminative features. The proposed method uses only 35 interpretable features compared to thousands of parameters in deep learning models. With 96.9\% accuracy, the framework offers competitive performance while maintaining full transparency.