BEATFORMER: A Delay-Aware Cardiovascular Foundation Model for Beat-Resolved ECG–PPG Representation Learning

Anonymous (ICLR 2027 double-blind submission)

Summary

Organizes synchronized ECG and PPG as sequences of paired heartbeats anchored on shared R peaks. A delay-aware fusion module estimates a posterior over beat-specific ECG→PPG delay and gates bidirectional cross-modal attention by its confidence; an orthogonal beat–phase Transformer models within-beat morphology and across-beat rhythm with physical-time and rhythm-aware positional biases. Pretrained on 84.76M cardiac cycles; wins 9/15 downstream tasks vs existing FMs, PAT MAE 11.48 ms (−24.6%), −11.3% reconstruction RMSE, best denoising SNR gain in 13/15 conditions.