Optimising the dichotomy limit for left ventricular ejection fraction in selecting patients for defibrillator therapy after myocardial infarction.
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.
Yap
Yee Guan
YG
Department of Cardiological Sciences, St George's Hospital Medical School, London, UK. ygyap@aol.com
Duong
Trinh
T
Bland
J Martin
JM
Malik
Marek
M
Torp-Pedersen
Christian
C
Køber
Lars
L
Gallagher
Mark M
MM
Camm
A John
AJ
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*