Open Access Original research

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

Flávio Correa Pivatelli16, Marcio Antonio dos Santos16, Gislaine Buzzini Fernandes26, Marcio Gatti36, Luiz Carlos de Abreu4, Vitor E Valenti5, Luiz Carlos M Vanderlei5, Celso Ferreira4, Fernando Adami4, Tatiana Dias de Carvalho4, Carlos Bandeira de Mello Monteiro4 and Moacir Fernandes de Godoy167*

Author Affiliations

1 Serviço de Hemodinâmica e Cardiologia Intervencionista do Hospital de Base – Fundação Faculdade Regional de Medicina (FUNFARME), de São José do Rio Preto (SP) and Departamento de Cardiologia e Cirurgia Cardiovascular da Faculdade de Medicina de São José do Rio Preto (FAMERP), Av. Brigadeiro Faria Lima, 5416, 15090-000, São José do Rio Preto, SP, Brazil

2 Departamento de Enfermagem em Saúde Coletiva e Orientação Profissional (DESCOP) do Curso de Enfermagem da Faculdade de Medicina de São José do Rio Preto (FAMERP), Av. Brigadeiro Faria Lima, 5416, 15090-000, São José do Rio Preto, SP, Brazil

3 Departamento de Especialidades Cirúrgicas da Faculdade de Medicina de São José do Rio Preto (FAMERP), Av. Brigadeiro Faria Lima, 5416, 15090-000, São José do Rio Preto, SP, Brazil

4 Laboratório de Escrita Científica, Departamento de Morfologia e Fisiologia, Faculdade de Medicina do ABC, Av. Príncipe de Gales, 821, CEP 09060-650, Santo André, SP, Brazil

5 Programa de Pós-Graduação em Fisioterapia, Faculdade de Ciências e Tecnologia, Universidade Estadual Paulista, UNESP, Rua Roberto Simonsen, 305, 19060-900, Presidente Prudente, SP, Brazil

6 NUTECC – Núcleo Transdisciplinar para Estudo do Caos e da Complexidade (FAMERP), Av. Brigadeiro Faria Lima, 5416, 15090-000, São José do Rio Preto, SP, Brazil

7 Rua Garabed Karabashian 570, 15070-600, São José do Rio Preto, SP, Brazil

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International Archives of Medicine 2012, 5:31  doi:10.1186/1755-7682-5-31

Published: 30 October 2012

Abstract

Background

Decreased 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.

Methods

We 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.

Results

Coronary 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.

Conclusion

We 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.

Keywords:
Heart rate variability; Nonlinear dynamics; Coronary artery disease; Cardiovascular physiology; Stable angina