Heterogeneous autonomic-emotional interactions in somatization: phenotype-based analysis in psychocardiology outpatients

Objective Psychocardiology addresses the integration of cardiovascular and psychological disorders. Patients with somatization-predominant symptoms (e.g., chest tightness and palpitations) often exhibit autonomic dysfunction, yet prior research lacks systematic phenotype classification and mechanistic exploration. This study aimed to classify somatization-dominant phenotypes in a psychocardiology clinic, analyze variations in psychological burden, autonomic function, and quality of life (QoL), and examine emotional symptoms (anxiety/depression) as mediators in the autonomic–somatization pathway, stratified by cardiovascular disease (CVD) status. Methods This cross-sectional study (May 2024–September 2025) enrolled 303 patients (PHQ-15 ≥5) from a medical college hospital, categorized into pure somatization, postural orthostatic tachycardia syndrome (POTS), chronic fatigue, and orthostatic hypotension (OH). Assessments included psychological scales (GAD-7 and PHQ-9), autonomic measures (HRV: TP/LF/HF; CARTs), and QoL (SF-12). ANCOVA, multivariable regression, and mediation models (controlling for age, gender, and education) were applied. Results Among the 303 somatization-dominant patients included, pure somatization was the most prevalent phenotype (n=143, 47.2%), followed by chronic fatigue (n=94, 31.0%), POTS (n=46, 15.2%), and OH (n=20, 6.6%). Compared with the pure somatization group, the chronic fatigue group had the highest anxiety (GAD-7), depression (PHQ-9), and the poorest QoL (SF-12) (all P<0.001). POTS exhibited elevated HRV power (TP: 4444.00 [IQR: 2356.50–10594.00]) and greater orthostatic HR increase (P<0.01). The OH group manifested the lowest total HRV (TP: 975.50 [IQR: 472.00–2117.59]) and blunted autonomic reflexes (CARTs) (P<0.001). Mediation analysis revealed that anxiety mediated the associations between HRV indices (TP and LF) and somatization outcomes (competitive mediation: HRV↑→anxiety↑→symptom burden↑, but HRV↑→symptom burden↓ after controlling for anxiety) in the full sample, while depression (PHQ-9) mediated the association between HRV indices (TP and LF) and somatization outcomes in CVD patients, and anxiety (GAD-7) mediated the associations between TP-related indices and somatization outcomes in non-CVD patients. Conclusion Somatization-dominant patients in psychocardiology exhibit heterogeneous psychophysiological profiles. Autonomic dysfunction influences symptom burden indirectly through emotional pathways (anxiety/depression), with CVD status altering mediation mechanisms. These findings support phenotype-stratified evaluation and emotion–autonomic integrated therapies for precision management.HRV Mediation via Anxiety/Depression