Sex Differences in Heart Rate Nonlinearity by Multifractal Multiscale Detrended Fluctuation Analysis

Area of Science:

• Cardiovascular Physiology
• Nonlinear Dynamics
• Biomedical Signal Processing

Background:

• Detrended fluctuation analysis (DFA) offers multifractal/multiscale (MFMS) insights into heart rate self-similarity.
• The capacity of MFMS DFA to capture nonlinear heart rate variability components remains underexplored.
• Understanding heart rate nonlinearity is crucial for assessing cardiovascular complexity and risk.

Purpose of the Study:

• To develop MFMS DFA indices for quantifying short-term and long-term heart rate nonlinearity.
• To investigate potential sex-related differences in these nonlinear heart rate components.
• To explore the clinical relevance of MFMS DFA in cardiovascular risk stratification.

Main Methods:

• Recorded inter-beat-interval (IBI) series from 42 males and 42 females at rest.
• Applied MFMS DFA to original and phase-randomized surrogate series to estimate self-similarity coefficients.
• Calculated short-term (NL1) and long-term (NL2) nonlinearity indices based on scale-specific percentile distributions.

Main Results:

• MFMS DFA revealed significant short-term nonlinearity (NL1 > 50%) for q≥0 (except q=2).
• Distinct sex differences were observed in short-term nonlinearity at negative moment orders (q<0), particularly at q=-1 and q=-2.
• MFMS DFA identified nonlinear heart rate components at short scales, not apparent with traditional monofractal DFA.

Conclusions:

• MFMS DFA effectively quantifies nonlinear heart rate components, highlighting sex-specific differences.
• This advanced analysis provides novel insights into cardiovascular complexity beyond traditional methods.
• MFMS DFA holds promise for integrating with spectral methods to improve cardiovascular risk stratification in clinical settings.