title: Deceleration capacity of heart rate as a predictor of mortality after myocardial infarction: cohort study.
abstract: BACKGROUND
  Decreased vagal activity after myocardial infarction results in reduced heart-rate variability and increased risk of death. To distinguish between vagal and sympathetic factors that affect heart-rate variability, we used a signal-processing algorithm to separately characterise deceleration and acceleration of heart rate. We postulated that diminished deceleration-related modulation of heart rate is an important prognostic marker. Our prospective hypotheses were that deceleration capacity is a better predictor of risk than left-ventricular ejection fraction (LVEF) and standard deviation of normal-to-normal intervals (SDNN).
  
  
  METHODS
  We quantified heart rate deceleration capacity by assessing 24-h Holter recordings from a post-infarction cohort in Munich (n=1455). We blindly validated the prognostic power of deceleration capacity in post-infarction populations in London, UK (n=656), and Oulu, Finland (n=600). We tested our hypotheses by assessment of the area under the receiver-operator characteristics curve (AUC).
  
  
  RESULTS
  During a median follow-up of 24 months, 70 people died in the Munich cohort and 66 in the London cohort. The Oulu cohort was followed-up for 38 months and 77 people died. In the London cohort, mean AUC of deceleration capacity was 0.80 (SD 0.03) compared with 0.67 (0.04) for LVEF and 0.69 (0.04) for SDNN. In the Oulu cohort, mean AUC of deceleration capacity was 0.74 (0.03) compared with 0.60 (0.04) for LVEF and 0.64 (0.03) for SDNN (p<0.0001 for all comparisons). Stratification by dichotomised deceleration capacity was especially powerful in patients with preserved LVEF (p<0.0001 in all cohorts).
  
  
  CONCLUSIONS
  Impaired heart rate deceleration capacity is a powerful predictor of mortality after myocardial infarction and is more accurate than LVEF and the conventional measures of heart-rate variability.
authors.affiliation: Deutsches Herzzentrum München, Klinikum rechts der Isar, Technische Universität München, Germany.
authors.forename: Axel
authors.initials: A
authors.lastname: Bauer
authors.forename: Jan W
authors.initials: JW
authors.lastname: Kantelhardt
authors.forename: Petra
authors.initials: P
authors.lastname: Barthel
authors.forename: Raphael
authors.initials: R
authors.lastname: Schneider
authors.forename: Timo
authors.initials: T
authors.lastname: Mäkikallio
authors.forename: Kurt
authors.initials: K
authors.lastname: Ulm
authors.forename: Katerina
authors.initials: K
authors.lastname: Hnatkova
authors.forename: Albert
authors.initials: A
authors.lastname: Schömig
authors.forename: Heikki
authors.initials: H
authors.lastname: Huikuri
authors.forename: Armin
authors.initials: A
authors.lastname: Bunde
authors.forename: Marek
authors.initials: M
authors.lastname: Malik
authors.forename: Georg
authors.initials: G
authors.lastname: Schmidt
mesh_terms: D000368:Aged; D002316:Cardiotonic Agents / Q000627:therapeutic use; D015331:Cohort Studies; D003654:Deceleration; D015716:Electrocardiography, Ambulatory / Q000379:methods*; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000188:drug therapy / Q000401:mortality*; D011237:Predictive Value of Tests; D012372:ROC Curve; D012307:Risk Factors; D013318:Stroke Volume
chemical_list: D002316:Cardiotonic Agents