Sensitivity, specificity and predictive values of linear and nonlinear indices of heart rate variability in stable angina patients

Abstract

BackgroundDecreased heart rate variability (HRV) is related to higher morbidity and mortality. In this study we evaluated the linear and nonlinear indices of the HRV in stable angina patients submitted to coronary angiography.MethodsWe studied 77 unselected patients for elective coronary angiography, which were divided into two groups: coronary artery disease (CAD) and non-CAD groups. For analysis of HRV indices, HRV was recorded beat by beat with the volunteers in the supine position for 40 minutes. We analyzed the linear indices in the time (SDNN [standard deviation of normal to normal], NN50 [total number of adjacent RR intervals with a difference of duration greater than 50ms] and RMSSD [root-mean square of differences]) and frequency domains ultra-low frequency (ULF) ≤ 0,003 Hz, very low frequency (VLF) 0,003 – 0,04 Hz, low frequency (LF) (0.04–0.15 Hz), and high frequency (HF) (0.15–0.40 Hz) as well as the ratio between LF and HF components (LF/HF). In relation to the nonlinear indices we evaluated SD1, SD2, SD1/SD2, approximate entropy (−ApEn), α1, α2, Lyapunov Exponent, Hurst Exponent, autocorrelation and dimension correlation. The definition of the cutoff point of the variables for predictive tests was obtained by the Receiver Operating Characteristic curve (ROC). The area under the ROC curve was calculated by the extended trapezoidal rule, assuming as relevant areas under the curve ≥ 0.650.ResultsCoronary arterial disease patients presented reduced values of SDNN, RMSSD, NN50, HF, SD1, SD2 and -ApEn. HF ≤ 66 ms2, RMSSD ≤ 23.9 ms, ApEn ≤−0.296 and NN50 ≤ 16 presented the best discriminatory power for the presence of significant coronary obstruction.ConclusionWe suggest the use of Heart Rate Variability Analysis in linear and nonlinear domains, for prognostic purposes in patients with stable angina pectoris, in view of their overall impairment.

The effects of auditory stimulation with music on heart rate variability in healthy women

“…In addition, the ratio between these components (LF/HF) represents a value that is relative to each spectral component in relation to the total power minus the very low frequency (VLF) components. We calculated the spectral analysis using the Fast Fourier Transform algorithm (9). …”

Cardiac autonomic regulation during exposure to auditory stimulation with classical baroque or heavy metal music of different intensities

“…The spectral analysis was calculated using the Fast Fourier Transform algorithm. [15,16] The analysis in the time domain was performed by means of SDNN (standard deviation of normal-tonormal R-R intervals), the percentage of adjacent RR intervals with a difference of duration greater than 50 ms (pNN50) and RMSSD (root-mean square of differences between adjacent normal RR intervals in a time interval). The HRV analysis is a well-recognized method for investigating cardiac autonomic regulation, and HRV is able to detect a poor prognostic in patients with cardiac disorders.…”

Cardiac autonomic modulation adjustments in isometric exercise

“…They concluded that the active recovery after isometric exercise depends on the duration and frequency of contraction. Pivatelli et al 30 found decreased levels of HRV in patients with coronary artery disease in the rest condition. Patients with reduced HRV, as assessed by linear methods in the preoperative period of surgical myocardial revascularization, tend to have higher morbidity and mortality.…”