title: Ambulatory ECG-based T-wave alternans and heart rate turbulence can predict cardiac mortality in patients with myocardial infarction with or without diabetes mellitus.
abstract: BACKGROUND
  Many patients who survive a myocardial infarction (MI) remain at risk of sudden cardiac death despite revascularization and optimal medical treatment. We used the modified moving average (MMA) method to assess the utility of T-wave alternans (TWA) and heart rate turbulence (HRT) as risk markers in MI patients with or without diabetes mellitus (DM).
  
  
  METHODS
  We prospectively enrolled 248 consecutive patients: 96 with MI (post-MI patients); 77 MI with DM (post-MI + DM patients); 75 controls without cardiovascular disease (group control). Both TWA and HRT were measured on ambulatory electrocardiograms (AECGs). HRT was assessed by two parameters ─ turbulence onset (TO) and turbulence slope (TS). HRT was considered positive when both TO ≥0% and TS ≤2.5 ms/R-R interval were met. The endpoint was cardiac mortality.
  
  
  RESULTS
  TWA values differed significantly between MI and controls. Post-MI + DM patients had higher TWA values than post-MI patients (58 ± 21 μV VS 52 ± 18 μV, P = 0.029). Impaired HRT--increased TO and decreased TS were observed in MI patients with or without DM. During follow-up of 578 ± 146 days, cardiac death occurred in ten patients and three of them suffered sudden cardiac death (SCD). Multivariate analysis determined that a HRT-positive outcome [HR (95% CI): 5.01, 1.33-18.85; P = 0.017], as well as the combination of abnormal TWA (≥47 μV) and positive HRT had significant association with the endpoint [HR (95% CI): 9.08, 2.21-37.2; P = 0.002)].
  
  
  CONCLUSIONS
  This study indicates that AECGs-based TWA and HRT can predict cardiac mortality in MI patients with or without DM. Combined analysis TWA and HRT may be a convenient and useful method of identifying patients at high risk for cardiovascular death.
authors.affiliation: Department of Cardiology, The First Affiliated Hospital of China Medical University, Shenyang 110001, China.
authors.forename: Ren
authors.initials: R
authors.lastname: Li-na
authors.forename: Fang
authors.initials: F
authors.lastname: Xin-hui
authors.forename: Ren
authors.initials: R
authors.lastname: Li-dong
authors.forename: Gong
authors.initials: G
authors.lastname: Jian
authors.forename: Wang
authors.initials: W
authors.lastname: Yong-quan
authors.forename: Qi
authors.initials: Q
authors.lastname: Guo-xian
mesh_terms: D016022:Case-Control Studies; D016009:Chi-Square Distribution; D002681:China / Q000453:epidemiology; D016757:Death, Sudden, Cardiac / Q000209:etiology*; D048909:Diabetes Complications / Q000401:mortality*; D015716:Electrocardiography, Ambulatory; D006339:Heart Rate; D006801:Humans; D015999:Multivariate Analysis; D009203:Myocardial Infarction / Q000150:complications / Q000175:diagnosis* / Q000401:mortality* / Q000503:physiopathology; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D011446:Prospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors