Risk stratification for primary implantation of a cardioverter-defibrillator in patients with ischemic left ventricular dysfunction.
OBJECTIVE
The study was designed to develop a simple risk stratification score for primary therapy with an implantable cardioverter-defibrillator (ICD).


BACKGROUND
Current guidelines recommend primary ICD therapy in patients with a low ejection fraction (EF). However, the benefit of the ICD in the low EF population may not be uniform.


METHODS
Best-subset proportional-hazards regression analysis was used to develop a simple clinical risk score for the end point of all-cause mortality in patients allocated to the conventional therapy arm of MADIT (Multicenter Automatic Defibrillator Implantation Trial)-II after excluding a pre-specified subgroup of very high-risk (VHR) patients (defined by blood urea nitrogen [BUN] >or=50 mg/dl and/or serum creatinine >or=2.5 mg/dl). The benefit of the ICD was then assessed within risk score categories and separately in VHR patients.


RESULTS
The selected risk score model comprised 5 clinical factors (New York Heart Association functional class >II, age >70 years, BUN >26 mg/dl, QRS duration >0.12 s, and atrial fibrillation). Crude mortality rates in the conventional group were 8% and 28% in patients with 0 and >or=1 risk factors, respectively, and 43% in VHR patients. Defibrillator therapy was associated with a 49% reduction in the risk of death (p < 0.001) among patients with >or=1 risk factors (n = 786), whereas no ICD benefit was identified in patients with 0 risk factors (n = 345; hazard ratio 0.96; p = 0.91) and in VHR patients (n = 60; hazard ratio 1.00; p > 0.99).


CONCLUSIONS
Our data suggest a U-shaped pattern for ICD efficacy in the low-EF population, with pronounced benefit in intermediate-risk patients and attenuated efficacy in lower- and higher-risk subsets.
Goldenberg
Ilan
I
Department of Medicine, University of Rochester Medical Center, Rochester, New York 14642, USA. Ilan.Goldenberg@heart.rochester.edu
Vyas
Anant K
AK
Hall
W Jackson
WJ
Moss
Arthur J
AJ
Wang
Hongyue
H
He
Hua
H
Zareba
Wojciech
W
McNitt
Scott
S
Andrews
Mark L
ML
D000368:Aged; D016757:Death, Sudden, Cardiac / Q000453:epidemiology / Q000517:prevention & control; D017147:Defibrillators, Implantable; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications / Q000628:therapy*; D017063:Outcome Assessment, Health Care; D016016:Proportional Hazards Models; D018570:Risk Assessment / Q000379:methods*; D018487:Ventricular Dysfunction, Left / Q000209:etiology / Q000401:mortality / Q000628:therapy*