title: ECG quantification of myocardial scar and risk stratification in MADIT-II.
abstract: BACKGROUND
  Low left ventricular ejection fraction (LVEF) increases risk for both sudden cardiac death (SCD) and for heart failure (HF) death; however, implantable cardioverter-defibrillators (ICDs) reduce the incidence of SCD, not HF death. Distinguishing individuals at risk for HF death (non-SCD) versus SCD could improve ICD patient selection.
  
  
  OBJECTIVE
  This study evaluated whether electrocardiogram (ECG) quantification of myocardial infarction (MI) could discriminate risk for SCD versus non-SCD.
  
  
  METHODS
  Selvester QRS scoring was performed on 995 MADIT-II trial subjects' ECGs to quantify MI size. MIs were categorized as small (0-3 QRS points), medium (4-7) or large (≥ 8). Mortality, SCD and non-SCD rates in the conventional medical therapy (CMT) arm and mortality and ventricular tachycardia/fibrillation (VT/VF) rates in the ICD arm were analyzed by QRS score group. Both arms were analyzed to determine ICD efficacy by QRS score group.
  
  
  RESULTS
  In the CMT arm, mortality, SCD and non-SCD rates were similar across QRS score groups (P = 0.73, P = 0.92, and P = 0.77). The ICD arm showed similar rates of mortality (P = 0.17) and VT/VF (P = 0.24) across QRS score groups. ICD arm mortality was lower than CMT arm mortality across QRS score groups with greatest benefit in the large scar group.
  
  
  CONCLUSIONS
  Recently, QRS score was shown to be predictive of VT/VF in the SCD-HeFT population consisting of both ischemic and nonischemic HF and having a maximum LVEF of 35% versus 30% for MADIT-II. Our study found that QRS score did not add prognostic value in the MADIT-II population exhibiting relatively more severe cardiac dysfunction.
authors.affiliation: Duke University School of Medicine, Durham, NC.
authors.forename: Zak
authors.initials: Z
authors.lastname: Loring
authors.forename: Wojciech
authors.initials: W
authors.lastname: Zareba
authors.forename: Scott
authors.initials: S
authors.lastname: McNitt
authors.forename: David G
authors.initials: DG
authors.lastname: Strauss
authors.forename: Galen S
authors.initials: GS
authors.lastname: Wagner
authors.forename: James P
authors.initials: JP
authors.lastname: Daubert
mesh_terms: D000368:Aged; D001145:Arrhythmias, Cardiac / Q000150:complications / Q000503:physiopathology*; D053840:Brugada Syndrome; D000075224:Cardiac Conduction System Disease; D002921:Cicatrix / Q000150:complications / Q000503:physiopathology*; D016757:Death, Sudden, Cardiac / Q000517:prevention & control; D017147:Defibrillators, Implantable; D004562:Electrocardiography / Q000379:methods* / Q000706:statistics & numerical data; D005260:Female; D006329:Heart Conduction System / Q000002:abnormalities* / Q000503:physiopathology; D006333:Heart Failure / Q000517:prevention & control; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications / Q000503:physiopathology* / Q000628:therapy; D011379:Prognosis; D016016:Proportional Hazards Models; D018570:Risk Assessment; D012307:Risk Factors; D012720:Severity of Illness Index; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology
keywords: electrocardiography; electrophysiology; heart failure; implantable cardioverter-defibrillator; sudden death; tachyarrhythmias
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