title: Optimising the dichotomy limit for left ventricular ejection fraction in selecting patients for defibrillator therapy after myocardial infarction.
abstract: BACKGROUND
  The selection of patients for prophylactic implantable cardioverter-defibrilator (ICD) treatment after myocardial infarction (MI) remains controversial.
  
  
  OBJECTIVE
  To determine the optimum left ventricular ejection fraction (LVEF) dichotomy limit for ICD treatment in patients with a history of MI.
  
  
  RESULTS
  Data from the placebo arms of four randomised trials were pooled to create a cohort of 2828 patients (2206 men, mean (SD) age 65 (11) years) with reduced left ventricular function after MI. The median LVEF was 33% (range 6-40%). LVEF significantly predicted mortality. Each 10% reduction in LVEF <40% conferred a 42% increase in all-cause mortality, a 39% increase in arrhythmic cardiac mortality and a 49% increase in non-arrhythmic cardiac mortality over the 2-year period of follow-up (p<0.001 for all modes of mortality). As the LVEF progressively decreased from < or =40% to < or =10%, the data show a U-shaped relationship between the dichotomy limit for LVEF used and the number of patients who must be treated to prevent one arrhythmic death in 2 years. At an LVEF of 16-20%, more patients are likely to die from arrhythmic than non-arrhythmic cardiac deaths, whereas in those with LVEF < or =10% all deaths were non-arrhythmic. However, the total number of deaths substantially decreased with lower LVEF.
  
  
  CONCLUSIONS
  A trade-off exists between the sensitivity and positive predictive accuracy across a range of LVEF, and no single dichotomy limit is completely satisfactory. In patients with LVEF < or =10% ICD treatment was not beneficial as all patients in this subgroup died from non-arrhythmic causes. The use of a single dichotomy limit for LVEF alone is not sufficient in selecting patients for ICD treatment in the primary prevention of cardiac arrest.
authors.affiliation: Department of Cardiological Sciences, St George's Hospital Medical School, London, UK. ygyap@aol.com
authors.forename: Yee Guan
authors.initials: YG
authors.lastname: Yap
authors.forename: Trinh
authors.initials: T
authors.lastname: Duong
authors.forename: J Martin
authors.initials: JM
authors.lastname: Bland
authors.forename: Marek
authors.initials: M
authors.lastname: Malik
authors.forename: Christian
authors.initials: C
authors.lastname: Torp-Pedersen
authors.forename: Lars
authors.initials: L
authors.lastname: Køber
authors.forename: Mark M
authors.initials: MM
authors.lastname: Gallagher
authors.forename: A John
authors.initials: AJ
authors.lastname: Camm
mesh_terms: D000368:Aged; D001145:Arrhythmias, Cardiac / Q000517:prevention & control; D003362:Cost-Benefit Analysis; D017147:Defibrillators, Implantable / Q000191:economics; D005260:Female; D006801:Humans; D008297:Male; D015337:Multicenter Studies as Topic; D009203:Myocardial Infarction / Q000401:mortality / Q000503:physiopathology* / Q000628:therapy; D018579:Patient Selection; D011446:Prospective Studies; D016032:Randomized Controlled Trials as Topic; D018570:Risk Assessment; D012307:Risk Factors; D013318:Stroke Volume / Q000502:physiology*