Heart Rate Asymmetry in Disorders of Consciousness

Abstract

Disorders of consciousness include unresponsive wakefulness syndrome (UWS), defined by absent awareness, and minimally conscious state (MCS), characterized by fluctuating yet reproducible signs of awareness. Distinguishing these two conditions is clinically essential yet remains highly error-prone using standard behavioral assessments. Cardiac autonomic regulation is governed by bidirectional brain-heart interactions that are differentially disrupted across consciousness levels, positioning electrocardiography (ECG) signals as a promising non-invasive diagnostic modality. This study examines whether Heart Rate Asymmetry (HRA) features derived from resting-state ECG Poincare plots can distinguish MCS from UWS patients. Our results reveal statistically significant differences in multiple HRA features. Absolute Spearman’s rank correlation coefficients of these features to Coma Recovery Scale-Revised scores indicate moderate monotonic relationships (|r| = 0.42 for total HRA; |r| = 0.47 for longterm HRA). These findings indicate that nonlinear cardiac features carry diagnostic information beyond what standard heart rate variability analysis provides.