ECG-Mamba-V2: Architectural Refinements to a Bidirectional State Space Model for Multi-Label 12-Lead ECG Classification

State space models offer linear-time sequence modeling and are a promising backbone for multi-label 12-lead ECG classification, but the design choices that drive their accuracy remain unclear. This letter presents ECG-Mamba-V2, a set of empirical refinements to a bidirectional Vision Mamba encoder: the class token is appended at the end of the token sequence instead of the midpoint, the forward and backward scan outputs are summed without the conventional 1/2 scaling, and dropout is applied at a uniform rate across blocks. On PhysioNet/CinC Challenge 2021, ECG-Mamba-V2 reaches 0.6494 macro AUPRC and 0.9716 macro AUROC, against 0.6100 and 0.9646 for its predecessor, while using 34% fewer parameters and delivering 38% higher throughput; it wins all 15 paired runs.