title: Deceleration Capacity of Heart Rate Predicts Arrhythmic and Total Mortality in Heart Failure Patients.
abstract: BACKGROUND
  Deceleration capacity (DC) of heart rate proved an independent mortality predictor in postmyocardial infarction patients. The original method (DCorig) may produce negative values (9% in our analyzed sample). We aimed to improve the method and to investigate if DC also predicts the arrhythmic mortality.
  
  
  METHODS
  Time series from 221 heart failure patients was analyzed with DCorig and a new variant, the DCsgn, in which decelerations are characterized based on windows of four consecutive beats and not on anchors. After 41.2 months, 69 patients experienced sudden cardiac death (SCD) surrogate end points, while 61 died.
  
  
  RESULTS
  (SCD+ vs SCD-group) DCorig: 3.7 ± 1.6 ms versus 4.6 ± 2.6 ms (P = 0.020) and DCsgn: 4.9 ± 1.7 ms versus 6.1 ± 2.2 ms (P < 0.001). After Cox regression (gender, age, left ventricular ejection fraction, filtered QRS, NSVT≥1/24h, VPBs≥240/24h, mean 24-h QTc, and each DC index added on the model separately), DCsgn (continuous) was an independent SCD predictor (hazard ratio [H.R.]: 0.742, 95% confidence intervals (C.I.): 0.631-0.871, P < 0.001). DCsgn ≤ 5.373 (dichotomous) presented 1.815 H.R. for SCD (95% C.I.: 1.080-3.049, P = 0.024), areas under curves (AUC)/receiver operator characteristic (ROC): 0.62 (DCorig) and 0.66 (DCsgn), P = 0.190 (chi-square). Results for deceased versus alive group: DCorig: 3.2 ± 2.0 ms versus 4.8 ± 2.4 ms (P < 0.001) and DCsgn: 4.6 ± 1.4 ms versus 6.2 ± 2.2 ms (P < 0.001). In Cox regression, DCsgn (continuous) presented H.R.: 0.686 (95% C.I. 0.546-0.862, P = 0.001) and DCsgn ≤ 5.373 (dichotomous) presented an H.R.: 2.443 for total mortality (TM) (95% C.I. 1.269-4.703, P = 0.008).
  0.71 (DCorig) and 0.73 (DCsgn), P = 0.402.
  
  
  CONCLUSIONS
  DC predicts both SCD and TM. DCsgn avoids the negative values, improving the method in a nonstatistical important level.
authors.affiliation: First Division of Cardiology, Medical School, National and Kapodistrian University of Athens, Athens, Greece.
authors.forename: Petros
authors.initials: P
authors.lastname: Arsenos
authors.affiliation: Department of Computer Science and Engineering, University of Ioannina, Ioannina, Greece.
authors.forename: George
authors.initials: G
authors.lastname: Manis
authors.affiliation: First Division of Cardiology, Medical School, National and Kapodistrian University of Athens, Athens, Greece.
authors.forename: Konstantinos A
authors.initials: KA
authors.lastname: Gatzoulis
authors.affiliation: First Division of Cardiology, Medical School, National and Kapodistrian University of Athens, Athens, Greece.
authors.forename: Polychronis
authors.initials: P
authors.lastname: Dilaveris
authors.affiliation: First Division of Cardiology, Medical School, National and Kapodistrian University of Athens, Athens, Greece.
authors.forename: Theodoros
authors.initials: T
authors.lastname: Gialernios
authors.affiliation: First Division of Cardiology, Medical School, National and Kapodistrian University of Athens, Athens, Greece.
authors.forename: Athanasios
authors.initials: A
authors.lastname: Angelis
authors.affiliation: First Division of Cardiology, Medical School, National and Kapodistrian University of Athens, Athens, Greece.
authors.forename: Achileas
authors.initials: A
authors.lastname: Papadopoulos
authors.affiliation: First Division of Cardiology, Medical School, National and Kapodistrian University of Athens, Athens, Greece.
authors.forename: Erifili
authors.initials: E
authors.lastname: Venieri
authors.affiliation: Cardiology Department, "Elpis" General Hospital, Athens, Greece.
authors.forename: Athanasios
authors.initials: A
authors.lastname: Trikas
authors.affiliation: First Division of Cardiology, Medical School, National and Kapodistrian University of Athens, Athens, Greece.
authors.forename: Dimitris
authors.initials: D
authors.lastname: Tousoulis
mesh_terms: D000368:Aged; D001145:Arrhythmias, Cardiac / Q000401:mortality* / Q000503:physiopathology*; D016757:Death, Sudden, Cardiac; D003654:Deceleration; D004452:Echocardiography; D004562:Electrocardiography; D005260:Female; D006333:Heart Failure / Q000401:mortality* / Q000503:physiopathology*; D006339:Heart Rate / Q000502:physiology*; D000070276:Heart Rate Determination / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies
keywords: autonomic nervous system; deceleration capacity; heart rate dynamics; myocardial infarction; risk stratification; sudden cardiac death