title: Linear and nonlinear analysis of heart rate variability in coronary disease.
abstract: OBJECTIVE
  Coronary artery disease (CAD) and acute myocardial infarction (AMI) are associated with a reduction of heart rate variability (HRV). The aim of this study was to compare the HRV of CAD patients with and without AMI (CAD-AMI) with health-matched controls by linear (spectral analysis) and nonlinear [Shannon entropy (SE), conditional entropy (CE) and symbolic analysis (SA)] analysis.
  
  
  METHODS
  Fifty-eight men were divided into three groups: healthy (n = 19, 57 ± 4 years), CAD (n = 20, 56 ± 10 years) and CAD-AMI (n = 19, 54 ± 12 years). The RR intervals were recorded at rest in the supine position for 10 min with an HR monitor (Polar(®)S810i). A series of 250 beats was selected to analyze variance, spectral analysis, SE, CE [complexity index (CI), normalized CI (NCI)] and SA (0V, 1V, 2LV and 2ULV patterns), as well as 0V (no significant variation) and 2ULV (two significant unlike variations), which reflect sympathetic and vagal modulation, respectively. One-way ANOVA (or the Kruskal-Wallis test when appropriate) and Pearson correlation were used.
  
  
  RESULTS
  The CAD group had higher body mass index and weight than the CAD-AMI group, but no differences were found between the healthy and AMI groups. There were no differences between the groups regarding linear and nonlinear analysis. The 0V and 2ULV patterns were significantly correlated with the SE, CI and NCI of the three groups.
  
  
  CONCLUSIONS
  There was no difference between the groups regarding cardiac autonomic modulation by linear and nonlinear methods, which may be due to beta-blocker use, coronary angioplasty and the exercise capacity of healthy subjects.
authors.affiliation: Laboratory of Cardiovascular Physiotherapy, Nucleus of Research in Physical Exercise, Federal University of São Carlos (UFSCar), Via Washington Luiz, Km 235, São Carlos, SP 13565-905, Brazil.
authors.forename: Victor Ribeiro
authors.initials: VR
authors.lastname: Neves
authors.forename: Anielle Cristhine Medeiros
authors.initials: AC
authors.lastname: Takahashi
authors.forename: Michele Daniela Borges
authors.initials: MD
authors.lastname: do Santos-Hiss
authors.forename: Antti Mikael
authors.initials: AM
authors.lastname: Kiviniemi
authors.forename: Mikko Paavo
authors.initials: MP
authors.lastname: Tulppo
authors.forename: Silvia Cristina Garcia
authors.initials: SC
authors.lastname: de Moura
authors.forename: Marlus
authors.initials: M
authors.lastname: Karsten
authors.forename: Audrey
authors.initials: A
authors.lastname: Borghi-Silva
authors.forename: Alberto
authors.initials: A
authors.lastname: Porta
authors.forename: Nicola
authors.initials: N
authors.lastname: Montano
authors.forename: Aparecida Maria
authors.initials: AM
authors.lastname: Catai
mesh_terms: D000328:Adult; D000368:Aged; D015897:Comorbidity; D003324:Coronary Artery Disease / Q000188:drug therapy / Q000453:epidemiology / Q000503:physiopathology*; D003430:Cross-Sectional Studies; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D017711:Nonlinear Dynamics