Depressive Symptoms are Associated with Heart Rate Variability Independently of Fitness: A Cross-Sectional Study of Patients with Heart Failure

BACKGROUND: Depression is associated with reduced heart rate variability (HRV) in healthy and cardiac samples, which may be accounted for by physical fitness. In a small sample of cardiac patients, activity and fitness levels attenuated the relationship between HRV and depression. In the current study of heart failure (HF) patients, we hypothesized that depressive symptoms and HRV would be inversely related and physical fitness would attenuate this association. PURPOSE: To determine if previous associations among depressive symptoms, physical fitness, and HRV would replicate in a sample of HF patients. METHODS: The sample consisted of HF patients (N = 125) aged 68.55 ± 8.92 years, 68.8% male, and 83.2% Caucasian. The study was cross-sectional and a secondary analysis of a nonrandomized clinical trial (Trial Identifier: NCT00871897). Depressive symptoms were evaluated using the Beck Depression Inventory (BDI)-II, fitness with the 2 min step test (2MST), and HRV during a 10 min resting laboratory psychophysiology protocol. The dependent variable in hierarchical linear regressions was the root mean square of successive differences. RESULTS: Controlling for sex, age, β-blocker use, hypertension, and diabetes, higher BDI-II scores significantly predicted lower HRV, β = -.29, t(92) = -2.79, p < .01. Adding 2MST did not attenuate the relationship in a follow-up regression. CONCLUSION: Depressive symptoms were associated with lower HRV in HF patients, independent of physical fitness. Given the prevalence of depression and suppressed HRV common among HF patients, interventions addressing depressive symptoms and other predictors of poor outcomes may be warranted.