title: Heart rate variability is associated with haptoglobin phenotype in patients with coronary artery disease.
abstract: BACKGROUND
  Three haptoglobin phenotypes exist called Hp 1-1, Hp 2-2, and Hp 2-1. Patients carrying the haptoglobin 1 allele seem to be partly protected against coronary artery disease. An attenuated heart rate variability is associated with a poor outcome in patients with coronary artery disease. Therefore, we hypothesized that the presence of the haptoglobin 1 allele would be associated with a favourable heart rate variability.
  
  
  METHODS
  A cross-sectional study.
  
  
  METHODS
  We included 255 patients who were referred for elective coronary angiography as a result of suspected coronary artery disease, and all underwent 24-h electrocardiogram recordings to assess heart rate variability in the time domain. The haptoglobin phenotype was also determined in each patient.
  
  
  RESULTS
  There were 159 patients in the Hp 1-1 and Hp 2-1 groups and 98 patients in the Hp 2-2 group. The two groups were comparable with respect to clinical parameters. However, the Hp 2-2 group had significantly lower 24-h heart rate variability values compared with the other group (RR 882 versus 921 ms, P=0.02; RMSSD 26 versus 30 ms, P<0.01; pNN50 6 versus 9%, P=0.01). Furthermore, Hp 2-2 was independently and negatively associated with heart rate variability (P=0.02).
  
  
  CONCLUSIONS
  Hp 2-2 was associated with an attenuated heart rate variability in patients with coronary artery disease that may help to explain other results reporting a poor prognosis in Hp 2-2 patients.
authors.affiliation: Department of Nephrology, Aalborg Hospital, Aalborg, Denmark. jhc@dadlnet.dk
authors.forename: Jeppe Hagstrup
authors.initials: JH
authors.lastname: Christensen
authors.forename: Henrik Bygum
authors.initials: HB
authors.lastname: Krarup
authors.forename: Sam
authors.initials: S
authors.lastname: Riahi
authors.forename: Egon
authors.initials: E
authors.lastname: Toft
authors.forename: Erik Berg
authors.initials: EB
authors.lastname: Schmidt
mesh_terms: D000368:Aged; D003324:Coronary Artery Disease / Q000503:physiopathology*; D004562:Electrocardiography; D005260:Female; D005838:Genotype; D006242:Haptoglobins / Q000235:genetics / Q000502:physiology*; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D011379:Prognosis
chemical_list: D006242:Haptoglobins