title: Predictors of sudden cardiac death and appropriate shock in the Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure (COMPANION) Trial.
abstract: BACKGROUND
  The factors that determine the risk for sudden death or implantable cardioverter defibrillator therapy in patients receiving cardiac resynchronization therapy (CRT) therapies are largely unknown.
  
  
  RESULTS
  We hypothesized that clinical measures of heart failure severity and the presence of comorbid conditions would predict the risk of malignant arrhythmias in the 1520 patients enrolled in the Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure (COMPANION) Trial. Outcomes in the CRT group after implantable cardioverter defibrillator therapy were also evaluated. The CRT-defibrillator device reduced the risk of sudden death by 56% compared with drug therapy (17 of 595 [2.9%] versus 18 of 308 [5.8%], P<0.02). CRT therapy was not associated with sudden death risk reduction (48 of 617 [7.8%]). Other factors associated with reduced sudden death risk were left ventricular ejection fraction >20% (HR, 0.55 [95% CI, 0.35 to 0.87]; P=0.01), QRS duration >160 ms (HR, 0.63 [95% CI, 0.40 to 0.997]; P=0.05), and female gender (HR, 0.56 [95% CI, 0.34 to 0.94]; P=0.003). The risk for sudden death was increased by advanced New York Heart Association class IV heart failure (HR, 2.62 [95% CI, 1.61 to 4.26]; P<0.011) and renal dysfunction (HR, 1.69 [95% CI, 1.06 to 2.69]; P=0.03). An appropriate shock was experienced in 88 (15%) of the 595 CTR-D patients. In the CRT-defibrillator patients, female gender (HR, 0.54 [95 % CI, 0.31 to 0.94]; P=0.03) and use of neurohormonal antagonists were associated with reduced risk. Class IV heart failure status increased risk. Appropriate implantable cardioverter defibrillator therapy was positively associated with risk of death or all-cause hospitalization (HR, 1.57; P<0.002), pump failure death or hospitalization (HR, 2.35; P<0.001), and sudden death (HR, 2.99; P=0.03), but not total mortality (HR, 1.3; P=0.28).
  
  
  CONCLUSIONS
  In CRT candidates, sudden cardiac death risk is associated with higher New York Heart Association class and renal dysfunction. In CRT-defibrillator recipients, reduction in the risk of an appropriate shock is associated with medical therapy with neurohormonal antagonists, female gender, and New York Heart Association functional class III versus IV clinical status. Shock therapy was associated with worse outcome.
authors.affiliation: Keck School of Medicine, University of Southern California, Los Angeles, CA, USA. saxon@usc.edu
authors.forename: Leslie A
authors.initials: LA
authors.lastname: Saxon
authors.forename: Michael R
authors.initials: MR
authors.lastname: Bristow
authors.forename: John
authors.initials: J
authors.lastname: Boehmer
authors.forename: Steven
authors.initials: S
authors.lastname: Krueger
authors.forename: David A
authors.initials: DA
authors.lastname: Kass
authors.forename: Teresa
authors.initials: T
authors.lastname: De Marco
authors.forename: Peter
authors.initials: P
authors.lastname: Carson
authors.forename: Lorenzo
authors.initials: L
authors.lastname: DiCarlo
authors.forename: Arthur M
authors.initials: AM
authors.lastname: Feldman
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Galle
authors.forename: Fred
authors.initials: F
authors.lastname: Ecklund
mesh_terms: D000368:Aged; D002304:Cardiac Pacing, Artificial / Q000706:statistics & numerical data*; D016757:Death, Sudden, Cardiac / Q000453:epidemiology* / Q000517:prevention & control; D004554:Electric Countershock / Q000706:statistics & numerical data*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D018579:Patient Selection; D018570:Risk Assessment; D012770:Shock, Cardiogenic / Q000453:epidemiology* / Q000628:therapy; D016019:Survival Analysis; D013997:Time Factors; D016896:Treatment Outcome