title: Spontaneous baroreflex sensitivity: prospective validation trial of a novel technique in survivors of acute myocardial infarction.
abstract: BACKGROUND
  Low baroreflex sensitivity (BRS) indicates poor prognosis after acute myocardial infarction. Noninvasive BRS assessment is complicated by nonstationarities and noise in electrocardiogram and pressure signals. Phase-rectified signal averaging is a novel signal processing technology overcoming these problems.
  
  
  OBJECTIVE
  To prospectively validate a BRS measure (baroreflex sensitivity assessed by means of phase-rectified signal averaging [BRS(PRSA)]) based on this technology.
  
  
  METHODS
  Nine hundred forty-one consecutive acute myocardial infarction survivors aged 80 years or younger in sinus rhythm were prospectively enrolled at 2 German university hospitals. All patients underwent 30-minute recordings of electrocardiogram and arterial blood pressures (Portapres; TNO-TPD Biomedical Instrumentation, Amsterdam, Netherlands) within the first 2 weeks after myocardial infarction. BRS(PRSA) was prospectively dichotomized at 1.58 ms/mm Hg. Primary end point was all-cause mortality at 5 years. Multivariable analyses included Global Registry of Acute Coronary Events score (dichotomized at ≥120), sex, BRS(PRSA), left ventricular ejection fraction (dichotomized at ≤35%), and diabetes mellitus. BRS(PRSA) was compared with 3 standard noninvasive BRS measures, that is, the sequence method, the transfer function method, and the correlation method.
  
  
  RESULTS
  During follow-up, 72 patients (7.7%) died. BRS(PRSA) stratified the study population into a high-risk group of 405 patients (≤1.58 ms/mm Hg) with an estimated 5-year mortality of 14.2% and a low-risk group of 536 patients (>1.58 ms/mm Hg) with a 5-year mortality of 2.8% (P <.0001). On multivariable analysis, BRS(PRSA) ≤ 1.58 ms/mm Hg was associated with a hazard ratio of 3.1 (confidence interval 1.7-5.6; P = .001). Predictive power of BRS(PRSA) ≤ 1.58 ms/mm Hg was particularly strong in patients with a Global Registry of Acute Coronary Events score of ≥120 or with a left ventricular ejection fraction of ≤35%.
  
  
  CONCLUSIONS
  BRS(PRSA) is a powerful and independent predictor of mortality in postinfarction patients especially when assessed in patients with a Global Registry of Acute Coronary Events score of ≥120 or a left ventricular ejection fraction of ≤35%.
authors.affiliation: Medizinische Klinik und Deutsches Herzzentrum München der Technischen Universität München, Munich, Germany.
authors.forename: Petra
authors.initials: P
authors.lastname: Barthel
authors.forename: Axel
authors.initials: A
authors.lastname: Bauer
authors.forename: Alexander
authors.initials: A
authors.lastname: Müller
authors.forename: Katharina M
authors.initials: KM
authors.lastname: Huster
authors.forename: Jørgen K
authors.initials: JK
authors.lastname: Kanters
authors.forename: Vijayapraveena
authors.initials: V
authors.lastname: Paruchuri
authors.forename: Xiaoyun
authors.initials: X
authors.lastname: Yang
authors.forename: Kurt
authors.initials: K
authors.lastname: Ulm
authors.forename: Marek
authors.initials: M
authors.lastname: Malik
authors.forename: Georg
authors.initials: G
authors.lastname: Schmidt
mesh_terms: D000368:Aged; D017704:Baroreflex / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D003925:Diabetic Angiopathies / Q000401:mortality* / Q000503:physiopathology*; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009203:Myocardial Infarction / Q000401:mortality* / Q000503:physiopathology*; D018579:Patient Selection; D011446:Prospective Studies; D012372:ROC Curve; D012815:Signal Processing, Computer-Assisted