Circadian Activity Disruption in Cardiac Remodeling Patients Underlies Autonomic Dysfunction in Heart Failure

Figures

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  Figure 1. Flowchart of patient selection. * Control group participants were matched to cases by sex.

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  Figure 2. Variation in HRV time-domain parameters between groups across 24 h. CR patients exhibited an overall shift toward altered autonomic balance. The sympathetic index (SNSi) and Stress Index (STi) displayed reduced oscillatory amplitude and an earlier acrophase compared with healthy subjects, indicating attenuated rhythmic sympathetic modulation. In contrast, the Parasympathetic Index (PNSi), SDNN, RMSSD, and pNN50 (PNN) demonstrated higher overall levels in CR subjects with preserved phase alignment relative to healthy individuals. Regarding heart rate dynamics, both minimum (MinHR) and maximum heart rate (MaxHR) exhibited reduced oscillatory amplitude in CR patients. Notably, MaxHR showed an earlier acrophase, indicating a phase advance in peak cardiac activation. These findings indicate diminished rhythmic autonomic modulation with selective phase alterations in CR.

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  Figure 3. Variation in HRV frequency-domain parameters between groups across 24 h. The CR group demonstrated markedly reduced oscillatory amplitude in normalized Low Frequency (LFn) and the LF/HF ratio (LFHF), indicating attenuated sympathovagal balance rhythmicity. Conversely, Absolute Low Frequency (LFab), Absolute High Frequency (HFab), Normalized High Frequency (HFn), Very Low Frequency (VLFab), and total power (Tpw) exhibited greater oscillatory amplitude in CR patients. The exaggerated oscillations in absolute spectral components suggest increased total variance but altered proportional distribution across bands. While absolute components increased, normalized indexes and LF/HF were reduced, indicating that relative spectral balance differs despite higher total power oscillation. CR is characterized by spectral redistribution and altered rhythmic coordination rather than uniform suppression of variability.

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  Figure 4. Variation in HRV nonlinear parameters between groups across 24 h. Nonlinear metrics provide a more sensitive characterization of altered rhythmic complexity. CR patients showed reduced oscillatory amplitude across multiple nonlinear domains: graphical (lower SD2/SD1 ratio), fractal (reduced α1 and α2), entropy-based (reduced AmpEn and SampEn), and Recurrence Determinism (reduced DET). Although some metrics exhibited preserved general rhythmic patterns, the amplitude of oscillation was consistently attenuated in CR. This indicates reduced dynamic adaptability and diminished multiscale complexity.