Association of heart rate variability and C-reactive protein in patients with depression.

Background: Depression has been shown to be correlated with cardiovascular (CV) morbidity and mortality. Inflammation and autonomic nervous system (ANS) dysfunction are possible causes. Numerous clinical studies have found an association between inflammatory pathways and the ANS. The aim of this study was to investigate the relationship between different heart rate variability (HRV) parameters and C-reactive protein (CRP) levels in depressed patients without concomitant diseases.

Materials And Methods: Sixty-five depressed patients who were not taking medication participated in this cross-sectional study. The Tenth Revision of the International Classification of Diseases and Related Health Problems (ICD-10) categorization of mental and behavioral disorders served as the basis for the diagnosis of depression. HRV processing and analysis were performed using ADInstrument's Pro LabChart (PowerLab 8Pro) data analysis software. HRV was recorded for 5 min in an upright sitting position using a lead II electrocardiogram (ECG) (short-term HRV). CRP levels were measured using an ELISA (enzyme-linked immunosorbent assay) test.

Results: None of the measures of HRV showed a significant relationship with pulse rate, systolic blood pressure, diastolic blood pressure, or body mass index (BMI). Weight and BMI were strongly positively related ( = 0.420, = 0.003) to pRR50 (percentage of successive RR intervals differing by more than 50 ms). Very low frequency (VLF), low frequency (LF), and the LF/HF (high frequency) ratio were all strongly positively correlated with CRP ( = 0.595, = 0.001), whereas HF was also significantly negatively correlated ( = 0.383, = 0.007). CRP had a significant negative correlation with the logarithm (ln) HF and a significant positive correlation with lnVLF, lnLF, and lnLF/HF.

Conclusion: Measurement of resting HRV and CRP may be helpful in detecting CV disease in depressed patients. Low HRV and elevated serum CRP should prompt physicians to begin treatment for risk CV as soon as possible.