ORIGINAL ARTICLE The Allan factor: a new model of mathematical interpretation of heart rate variability in stable coronary artery disease. Preliminary results

Abstract

Introduction: The current analysis of heart rate variability (HRV) is one of the noninvasive methods of cardiovascular system assessment. The quantitative characteristics of the RR interval sequence and its dynamics are still under development as regards measurement techniques and development of new HRV interpretation models. The practical clinical application of the standard measurements is still insufficient and improvement of sensitivity and specificity of HRV parameters is needed. Aim: To assess a novel mathematical model of HRV interpretation and compare it with standard HRV measurements for patients with stable coronary artery disease (CAD), based on the virtual instrumentation technique. Methods: The study group consisted of 24 patients with CAD confirmed by coronary angiography and a control group of 15 volunteers. Short-term electrocardiographic signals were recorded by a computer system and analysed for estimation of several HRV descriptors in time, frequency and combined time-frequency domains. Calculations included standard HRV measures and the Allan factor, a parameter based on the Haar wavelet transform. Results: None of the investigated measurements derived from power spectral analysis has shown a statistically significant difference between healthy controls and patients with CAD, with the exception of rMSSD (Wilcoxon test: supine position *p=0.0018, erect position p=0.0708; discriminant function analysis: supine position *p=0.0069, erect position p=0.7851). Compared with standard HRV variables, the Allan factor better discriminated patients with CAD from healthy subjects (Wilcoxon test: supine position *p=0.0172, erect position *p=0.0001; discriminant function analysis: supine position p=0.8962, erect position *p=0.0200). Conclusions: The observations related to the novel parameter based on combined time and frequency domains may provide better quantitative measurements of heart rate variability in patients with coronary artery disease and require further investigations to assess their sensitivity and specificity.