title: Heart rate turbulence as a predictor of cardiac mortality and arrhythmic events in patients with dilated cardiomyopathy: a prospective study.
abstract: BACKGROUND
  Few studies have described the clinical usefulness of heart rate turbulence (HRT), an autonomic predictor of mortality, in stratifying patients with dilated cardiomyopathy (DCM) at risk of cardiac mortality and arrhythmic events. We prospectively assessed the utility of HRT for risk stratification in patients with ischemic or nonischemic DCM.
  
  
  METHODS
  We enrolled 375 consecutive patients with DCM including ischemic (n = 241) and nonischemic causes (n = 134). HRT was measured using an algorithm based on routine 24-hour Holter electrocardiograms, assessing 2 parameters: turbulence onset (TO) and turbulence slope (TS). HRT was considered positive when both TO was > or = 0% and TS was < or = 2.5 ms/R-R interval. The primary endpoint was defined as cardiac mortality and the secondary endpoint as occurrence of hemodynamically stable sustained ventricular tachyarrhythmias.
  
  
  RESULTS
  Of patients enrolled, 83 patients (22.1%) were not utilized for HRT assessment because there were too few ventricular premature beats, or for other reasons. Eighty-one of 292 patients (27.7%) were HRT-positive. During follow-up of 445 +/- 216 days, 30 patients (10.3%) reached the primary endpoint and 17 patients, the secondary endpoint. The hazard ratio (HR) of patients with an HRT-positive outcome was 6.4 (95%CI, 3.0-14.1; P < 0.0001) for the primary endpoint and 5.1 (95%CI, 2.8-9.3; P < 0.0001) for combined endpoints. On subanalysis, HRT positivity was significantly associated in both the ischemic and nonischemic DCM patients with both the primary endpoint (HR = 4.9, P = 0.0006 and HR = 12.3, P = 0.002, respectively) and with combined endpoints.
  
  
  CONCLUSIONS
  HRT is a powerful risk stratification marker for cardiac mortality and arrhythmic events in patients with DCM whether ischemia is present or not.
authors.affiliation: Second Department of Internal Medicine, Kyorin University School of Medicine, Mitaka, Tokyo, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Miwa
authors.forename: Takanori
authors.initials: T
authors.lastname: Ikeda
authors.forename: Katsura
authors.initials: K
authors.lastname: Sakaki
authors.forename: Mutsumi
authors.initials: M
authors.lastname: Miyakoshi
authors.forename: Haruhisa
authors.initials: H
authors.lastname: Ishiguro
authors.forename: Takehiro
authors.initials: T
authors.lastname: Tsukada
authors.forename: Atsuko
authors.initials: A
authors.lastname: Abe
authors.forename: Hisaaki
authors.initials: H
authors.lastname: Mera
authors.forename: Satoru
authors.initials: S
authors.lastname: Yusu
authors.forename: Hideaki
authors.initials: H
authors.lastname: Yoshino
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002311:Cardiomyopathy, Dilated / Q000150:complications / Q000401:mortality* / Q000503:physiopathology*; D015716:Electrocardiography, Ambulatory; D005260:Female; D006339:Heart Rate; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D011446:Prospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D017180:Tachycardia, Ventricular / Q000209:etiology* / Q000401:mortality* / Q000503:physiopathology; D013997:Time Factors