Autonomic nervous system (ANS) dysregulation is an important pathophysiological mechanism in patients with chronic obstructive pulmonary disease (COPD). Heart rate variability (HRV) is a common index for ANS, and HRV has been used to explore the association between ANS and clinical illnesses. This study aimed to explore the group differences in HRV, depression, anxiety, and quality of life between participants with COPD and healthy controls (HC group), and whether emotion plays a mediating role between HRV and quality of life in participants with COPD. A total of ninety-six participants with COPD and 59 participants in the HC group completed the Beck Depression Inventory-II (BDI-II), Beck Anxiety Inventory (BAI), and Saint George’s Respiratory Questionnaire (SGRQ). Assessment of spirometry pulmonary function and five minute lead II electrocardiography (ECG) were also performed under the resting baseline. The COPD group had higher depression scores (F = 4.10, p = 0.008), and a lower quality of life (F = 14.44, p < 0.001) and HRV indices (such as standard deviation of RR intervals (F = 5.49, p < 0.05) and low frequency (F = 3.03, p < 0.05)) compared to the HC group. Sympathetic activation was positively correlated with depression (r = 0.312, p < 0.01), anxiety (r = 0.420, p < 0.001), and poor quality of life (r = 0.467, p < 0.001) in the COPD group. After controlling for age and sex, anxiety (β = 0.585, p < 0.001) and sympathetic activation (β = 0.231, p < 0.05) positively predicted poor quality of life, and lung function (β = −0.251, p < 0.01) negatively predicted poor quality of life. Therefore, anxiety is a mediator between sympathetic activation and quality of life. Emotional and HRV screening should be applied to COPD patients in clinical practice, and emotional management or HRV biofeedback training can be used to improve anxiety and HRV for future studies.

Heart rate variability (HRV) is related to cardiac vagal control and emotional regulation and an index for cardiac vagal control and cardiac autonomic activity. This study aimed to develop the Taiwan HRV normative database covering individuals aged 20 to 70 years and to assess its diagnosing validity in patients with major depressive disorder (MDD). A total of 311 healthy participants were in the HRV normative database and divided into five groups in 10-year age groups, and then the means and standard deviations of the HRV indices were calculated. We recruited 272 patients with MDD for cross-validation, compared their HRV indices with the normative database, and then converted them to Z-scores to explore the deviation of HRV in MDD patients from healthy groups. The results found a gradual decline in HRV indices with advancing age in the HC group, and females in the HC group exhibit higher cardiac vagal control and parasympathetic activity than males. Conversely, patients in the MDD group demonstrate lower HRV indices than those in the HC group, with their symptoms of depression and anxiety showing a negative correlation with HRV indices. The Taiwan HRV normative database has good psychometric characteristics of cross-validation.