title: Electrophysiology-guided defibrillator implantation early after ST-elevation myocardial infarction.
abstract: BACKGROUND
  Sudden death risk is highest early after myocardial infarction (MI). Inducible ventricular tachycardia (VT) confers increased risk of spontaneous ventricular arrhythmias.
  
  
  OBJECTIVE
  The purpose of this study was to evaluate outcomes of electrophysiology (EP)-guided defibrillator implantation early after ST-elevation MI in patients with ejection fraction ≤40%.
  
  
  METHODS
  EP study was performed 9 days after MI (n = 360). Predischarge defibrillator was recommended if VT with cycle length ≥200 ms was induced with ≤4 extrastimuli (EP-positive [EP(pos)], n = 142). EP-negative (EP(neg)) patients were discharged without a defibrillator (n = 218). Primary endpoint was either sudden death or spontaneous ventricular arrhythmia.
  
  
  RESULTS
  Defibrillator was implanted in 71% of EP(pos) patients (median 21 days post-MI) and withheld in 94% of EP(neg) patients. At 2 years, primary endpoint was 4.3% in the EP(neg) group and 22% in the EP(pos) group (adjusted hazard ratio 0.46, P = .035, EP(neg) vs EP(pos)). Lack of a defibrillator in EP(pos) patients conferred a fourfold increased risk of sudden death (P = .014). EP(neg) patients without a defibrillator were at significantly lower risk for the primary endpoint than were EP(pos) patients without a defibrillator (adjusted HR 0.34, P = .011). Short inducible VT cycle length (200-230 ms) and use of the fourth extrastimulus identified patients at significant arrhythmic risk.
  
  
  CONCLUSIONS
  EP study performed early after MI identified patients at significant long-term arrhythmic risk at a critical time after MI in whom defibrillator implantation was protective. A large majority of patients (EP(neg); two thirds) were at significantly lower risk of arrhythmic events without a defibrillator in the long term.
authors.affiliation: Department of Cardiology, Westmead Hospital, Sydney, New South Wales, Australia.
authors.forename: Saurabh
authors.initials: S
authors.lastname: Kumar
authors.forename: Gopal
authors.initials: G
authors.lastname: Sivagangabalan
authors.forename: Sarah
authors.initials: S
authors.lastname: Zaman
authors.forename: Elizabeth B
authors.initials: EB
authors.lastname: West
authors.forename: Arun
authors.initials: A
authors.lastname: Narayan
authors.forename: Aravinda
authors.initials: A
authors.lastname: Thiagalingam
authors.forename: Pramesh
authors.initials: P
authors.lastname: Kovoor
mesh_terms: D000368:Aged; D054849:Cardiac Electrophysiology; D017147:Defibrillators, Implantable; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000503:physiopathology* / Q000628:therapy*; D013318:Stroke Volume; D013997:Time Factors; D016896:Treatment Outcome