Evaluating the efficacy of photoplethysmography-derived stiffness index, sine-waveform ratio, and heart rate variability total power for cardiovascular health assessment

Introduction This study aimed to predict risk of cardiovascular disease (CVD) in participants unaware of their cardiovascular health using a convenient approach. Methods Continuous 100-second photoplethysmography (PPG) signals were recorded from 144 participants. The subjects were subsequently categorized based on the presence or absence of CVD. The proportions of abnormal stiffness index (SI), the sine-waveform ratio (SIN ratio), a morphological index of PPG waveform regularity used as a marker for cardiovascular pathological aging, and total power (TP), derived from heart rate variability (HRV) frequency-domain analysis to reflect autonomic nervous system activity, were compared. Results A total of 144 participants were enrolled in this study (CVD group, n = 54; healthy control group, n = 90). CVD group had higher SIN ratio (37.4 ± 27.8% vs. 21 ± 23.9%) and lower TP (1587.0 ± 262.9 vs. 1804.7 ± 261.7ms²) compared to healthy controls ( p < 0.001). CVD group had higher rates of abnormal SI (46% vs. 24%) and SIN ratio > 40% (42.6% vs. 23.5%), all p < 0.01. The combination of abnormal SI values, SIN ratio > 40%, and TP < 1500 ms² indicated a high likelihood of CVD ( p < 0.001). Conclusion PPG-derived SI, SIN ratio, and TP are valuable indicators that are potentially associated with cardiovascular health. Our results provided a convenient, inexpensive, and automated approach for preliminary assessment of the presence of CVD. Further large-scale studies are needed to validate these findings.