title: Noninvasive risk assessment early after a myocardial infarction the REFINE study.
abstract: OBJECTIVE
  This study sought to determine whether combined assessment of autonomic tone plus cardiac electrical substrate identifies most patients at risk of serious events after myocardial infarction (MI) and to compare assessment at 2 to 4 weeks versus 10 to 14 weeks after MI.
  
  
  BACKGROUND
  Methods to identify most patients at risk of serious events after MI are required.
  
  
  METHODS
  Patients (n = 322) with an ejection fraction (EF) <0.50 in the initial week after MI were followed up for a median of 47 months. Serial assessment of autonomic tone, including heart rate turbulence (HRT), electrical substrate, including T-wave alternans (TWA), and EF was performed, interpreted blinded, and categorized using pre-specified cut-points where available. The primary outcome was cardiac death or resuscitated cardiac arrest. All-cause mortality and fatal or nonfatal cardiac arrest were secondary outcomes.
  
  
  RESULTS
  Mean EF significantly increased over the initial 8 weeks after MI. Testing 2 to 4 weeks after MI did not reliably identify patients at risk, whereas testing at 10 to 14 weeks did. The 20% of patients with impaired HRT, abnormal exercise TWA, and an EF <0.50 beyond 8 weeks post-MI had a 5.2 (95% confidence interval [CI] 2.4 to 11.3, p < 0.001) higher adjusted risk of the primary outcome. This combination identified 52% of those at risk, with good positive (23%; 95% CI 17% to 26%) and negative (95%; 95% CI 93% to 97%) accuracy. Similar results were observed for the secondary outcomes.
  
  
  CONCLUSIONS
  Impaired HRT, abnormal TWA, and an EF <0.50 beyond 8 weeks after MI reliably identify patients at risk of serious events. (Assessment of Noninvasive Methods to Identify Patients at Risk of Serious Arrhythmias After a Heart Attack; http://www.clinicaltrials.gov/ct/show/NCT00399503?order=1; NCT00399503).
authors: Libin Cardiovascular Institute of Alberta, Calgary, Canada; Department of Community Health Sciences, University of Calgary, Calgary, Canada.
authors: Derek V
authors: DV
authors: Exner
authors: Katherine M
authors: KM
authors: Kavanagh
authors: Michael P
authors: MP
authors: Slawnych
authors: L Brent
authors: LB
authors: Mitchell
authors: Darlene
authors: D
authors: Ramadan
authors: Sandeep G
authors: SG
authors: Aggarwal
authors: Catherine
authors: C
authors: Noullett
authors: Allie
authors: A
authors: Van Schaik
authors: Ryan T
authors: RT
authors: Mitchell
authors: Mariko A
authors: MA
authors: Shibata
authors: Sajad
authors: S
authors: Gulamhussein
authors: James
authors: J
authors: McMeekin
authors: Wayne
authors: W
authors: Tymchak
authors: Gregory
authors: G
authors: Schnell
authors: Anne M
authors: AM
authors: Gillis
authors: Robert S
authors: RS
authors: Sheldon
authors: Gordon H
authors: GH
authors: Fick
authors: Henry J
authors: HJ
authors: Duff
mesh_terms: D000368:Aged; D017704:Baroreflex / Q000502:physiology; D004562:Electrocardiography / Q000379:methods*; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D006323:Heart Arrest / Q000209:etiology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications* / Q000401:mortality / Q000503:physiopathology*; D011237:Predictive Value of Tests; D018570:Risk Assessment / Q000379:methods; D013318:Stroke Volume / Q000502:physiology; D013997:Time Factors