Abstract
BACKGROUND: Autonomic nervous system (ANS) dysfunction appears in the course of both chronic heart failure (CHF) and depression. Comprehensive cardiac rehabilitation (CCR), apart from improving physical capacity, can reduce depressive symptoms and leads to the restoration of ANS function among CHF patients. The purpose was to evaluate the influence of the reversion of depression (measured by Beck Depression Inventory [BDI] score, cut point <10) and the physical capacity improvement (measured by peak oxygen consumption [peak VO2 ; ml/kg per minute]) on the sympathovagal balance (measured by low/high frequency ratio [LF/HF]) after CCR in CHF patients. METHODS: The study group comprised 111 CHF patients (New York Heart Association II-III; left ventricular ejection fraction ≤ 40%). Patients were randomized (2:1) to 8-week CCR based on Nordic walking training (five times weekly) at 40-70% of maximal heart rate, training group (TG) n = 77, or to control group (CG) n = 34. The effectiveness of CCR was assessed by changes-delta (Δ) in LF/HF, BDI score, and peak VO2 , as a result of comparing these parameters from the beginning and the end of the program. RESULTS: Eventually, 46 patients in TG and 23 patients in CG were eligible for simultaneous ANS and psychological status analysis. Only in TG the LF/HF decreased 2.06 ± 1.14 versus 1.19 ± 0.80 (P < 0.0001) and peak VO2 increased 16.83 ± 3.72 versus 19.14 ± 4.20 ml/kg per minute (P < 0.0001). Favorable results in CG were not observed. The differences between TG and CG were significant: Δpeak VO2 (P < 0.0001); ΔLF/HF (P = 0.0001). Depressive symptoms were substantially reduced in both groups (TG, P = 0.0006; CG, P = 0.0490). Nevertheless, the greatest improvement of sympathovagal balance was observed in patients whose depression was reversed, thanks to the CCR in comparison to other patients from TG and the entire CG. CONCLUSION: Positive effect of the sympatho-parasympathetic balance obtained during the home CCR based on Nordic walking training results from the additive effects of the reversion of depression and physical capacity improvement in CHF patients.