title: Comparison between invasive and non-invasive measurements of baroreflex sensitivity; implications for studies on risk stratification after a myocardial infarction.
abstract: OBJECTIVE
  The ATRAMI (Autonomic Tone and Reflexes After Myocardial Infarction) study has proved the independent prognostic value of baroreflex sensitivity. A limitation of the traditional method of estimating baroreflex sensitivity by phenylephrine, is the need to monitor intra-arterial blood pressure. Our objective was to establish whether this invasive method of monitoring could be superseded by non-invasive methods, such as the Finapres device.
  
  
  RESULTS
  Patients with three repeated invasive and non-invasive baroreflex sensitivity measurements were selected from the ATRAMI database (n = 454). The mean of these measurements was taken as the baroreflex sensitivity estimate. The repeatability of both methods (standard deviation of the three measurements) decreased with increasing baroreflex sensitivity. There was no constant bias between invasive and non-invasive measurements (0. 22+/-2.2 ms. mmHg(-1), P = 0.42). The linear correlation was very high (r = 0.91, P < 0.01). The normalized 95% limits of agreement were -0.5 and 0.52. On survival analysis, invasive and non-invasive baroreflex sensitivity gave similar prognostic information (likelihood ratio: 155.6 (P = 0.007) and 155.0 (P = 0.006); risk ratio: 0.79 and 0.81, respectively). According to the ATRAMI cut-off points, 85% of patients were classified concordantly by the two methods. None of the patients at high (low) risk with the invasive method were classified as low (high) risk class by the non-invasive method.
  
  
  CONCLUSIONS
  Despite wide limits of agreement, invasive and non-invasive baroreflex sensitivity measurements are highly correlated and provide equivalent prognostic information.
authors.affiliation: Department of Biomedical Engineering, S. Maugeri Foundation, Institute of Care and Scientific Research, Rehabilitation Institute of Montescano, Pavia, Italy.
authors.forename: G D
authors.initials: GD
authors.lastname: Pinna
authors.forename: M T
authors.initials: MT
authors.lastname: La Rovere
authors.forename: R
authors.initials: R
authors.lastname: Maestri
authors.forename: A
authors.initials: A
authors.lastname: Mortara
authors.forename: J T
authors.initials: JT
authors.lastname: Bigger
authors.forename: P J
authors.initials: PJ
authors.lastname: Schwartz
mesh_terms: D001341:Autonomic Nervous System / Q000503:physiopathology*; D017704:Baroreflex / Q000502:physiology*; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000503:physiopathology*; D010656:Phenylephrine / Q000008:administration & dosage; D011237:Predictive Value of Tests; D011379:Prognosis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D014662:Vasoconstrictor Agents / Q000008:administration & dosage
chemical_list: D014662:Vasoconstrictor Agents; D010656:Phenylephrine