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Updated: Jun 8, 2026

Human Circadian Phenotyping and Diurnal Performance Testing in the Real World
Published on: April 7, 2020
Optimal timing in screening patients with congestive heart failure and healthy subjects during circadian observation
Tai-Lang Jong1, Ben Chang, Cheng-Deng Kuo
1Department of Electrical Engineering, National Tsing Hua University, Hsinchu, Taiwan, ROC.
Insights
This study identifies the optimal 7 PM to 9 PM window for screening congestive heart failure (CHF) patients using heart rate variability (HRV) analysis. The α1 parameter effectively distinguishes CHF from normal sinus rhythm (NSR) during this period.
Area of Science:
- Cardiology
- Biomedical Engineering
- Data Science
Background:
- Congestive heart failure (CHF) presents a significant healthcare challenge.
- Accurate and rapid screening of CHF patients is crucial for timely intervention.
- Circadian rhythm influences physiological parameters, including heart rate variability (HRV).
Purpose of the Study:
- To determine the optimal timing for screening congestive heart failure (CHF) patients using heart rate variability (HRV) during circadian observation.
- To evaluate the efficacy of the α1 parameter in detrended fluctuation analysis for distinguishing CHF from normal sinus rhythm (NSR).
- To assess the performance of a support vector machine (SVM) for CHF classification based on HRV parameters.
Main Methods:
- Utilized interbeat interval data from 29 CHF patients and 54 healthy subjects.
- Applied detrended fluctuation analysis (DFA) to calculate the α1 parameter of HRV.
- Employed the Fano factor to identify optimal screening times.
- Used a support vector machine (SVM) with leave-one-out cross-validation for classification.
- Analyzed ECG recordings of varying lengths (2–120 min).
Main Results:
- The α1 parameter of HRV effectively differentiates CHF patients from NSR subjects (Kruskal-Wallis test).
- The optimal screening period identified was between 7 PM and 9 PM.
- This finding remained robust across different ECG recording durations.
- SVM classification achieved superior performance for CHF detection during the 7 PM–9 PM window.
Conclusions:
- The 7 PM to 9 PM circadian period offers optimal timing for non-invasive screening of CHF patients.
- The α1 parameter derived from HRV analysis is a reliable indicator for CHF screening.
- These findings support the clinical application of HRV analysis for efficient CHF monitoring.
Abstract:
Congestive heart failure (CHF) is a major medical challenge in developed countries. In order to screen patients with CHF and healthy subjects during circadian observation, accurate judgment and fast response are imperative. In this study, optimal timing during circadian observation via the heart rate variability (HRV) was sought. We tested 29 CHF patients and 54 healthy subjects in the control group from the interbeat interval databases of PhysioBank. By invoking the α1 parameter in detrended fluctuation analysis of HRV, we found that it could be used as an indicator to screen the patients with CHF and subjects in normal sinus rhythm (NSR) under Kruskal-Wallis test. By invoking Fano factor, the optimal timing to screen CHF patients and healthy subjects was found to be from 7 PM to 9 PM during the circadian observation. In addition, this result is robust in a sense that the same result can be achieved by using different ECG recording lengths of 2, 5, 10, … , and 120 min, respectively. Furthermore, a support vector machine was employed to classify CHF and NSR with α1 parameter of a moving half-hour ECG recordings via leave-one-out cross validation. The results showed that the superlative screening performance was obtained in the 7 pm-9 pm period during circadian observation. It is believed that this result of optimal timing will be helpful in the non-invasive monitoring and screening of CHF patients and healthy subjects in the clinical practice.
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