Enhanced Brain-Heart Connectivity as a Precursor of Reduced State Anxiety after Therapeutic Virtual Reality Immersion

State anxiety involves transient feelings of tension and nervousness in response to threats, which can escalate into anxiety disorders if persistent. Despite treatments, 30%-50% of individuals show limited improvement, and neurophysiological mechanisms of treatment responsiveness remain unclear, requiring the development of objective biomarkers. In this study, multimodal electrophysiological parameters are monitored: heart rate variability (high frequency (HF), low frequency (LF), LF/HF ratio), EEG beta and alpha relative power, and brain-to-heart connectivity in participants with real-life state anxiety. Participants underwent a therapeutic intervention combining virtual-reality immersion, hypnotic script, and a breath control exercise. Real-life state anxiety is captured using the State-Trait Anxiety Inventory Form Y1 (STAI-Y1) scale before and after the intervention. Reduced anxiety is observed immediately after the intervention in 16 out of 27 participants. While all participants, independently of their STAI-Y1 score, showed increased heart rate variability (HRV) low frequency power, only treatment-responders displayed increased overall autonomic tone (high and low frequency HRV), increased midline beta power and brain-to-heart connectivity. Notably, the LF/HF ratio showed a significant linear relationship with anxiety reduction, with higher ratios linked to greater therapeutic response. These findings suggest that increased cognitive regulation of brain-to-heart connectivity can serve as a biomarker for therapeutic efficacy, with elevated midline beta power facilitating improved cardiac tone in responders.