title: The impact of myocardial viability on the clinical outcome of cardiac resynchronization therapy.
abstract: BACKGROUND
  Around 30% of patients do not respond to cardiac resynchronization therapy (CRT). Nonischemic cardiomyopathy has been identified as an independent predictor of response to CRT, probably due to the absence of compact scar.
  
  
  RESULTS
  The relationship between cardiac scar, ischemia, and hibernation (both at the left-ventricular pacing site and as a total burden) and response to CRT was studied in patients with ischemic cardiomyopathy using the perfusion-viability positron emission tomography (PET) test. Sixty-six patients with ischemic cardiomyopathy and traditional criteria for CRT were included. All patients underwent PET scan prior to CRT. Using PET, the amount and location of scarred, ischemic, and hibernating myocardium were characterized. No revascularization was indicated. Responders were defined by an improvement of left-ventricular ejection fraction (LVEF) >or= 5% and/or New York Heart Association (NYHA) class >or= 1 degree. During a mean follow-up of 26.2 +/- 22.2 months, there was a significant improvement in NYHA class and reverse remodeling in patients with the LV lead inserted remotely from the scar. However, reverse remodeling of a similar degree was present also in patients with extensive scarring including the lateral wall. The presence of ischemia, hibernation, or nontransmural scar at the pacing-site did not significantly modify the outcome of CRT as compared with viable myocardium. There were only 38% of CRT-nonresponders. Neither the extent of scar, ischemia, hibernation, or viability predicted outcome or mortality. Twenty patients died during the follow-up, one patient underwent heart transplant.
  
  
  CONCLUSIONS
  At follow-up, response to CRT is observed regardless of the presence of extensive scarring. Left ventricular (LV) pacing at sites with ischemia, hibernation, or nontransmural scar does not appear to modify the effect of CRT as compared to viable tissue.
authors.affiliation: Department of Cardiovascular Medicine, Cleveland Clinic, Cleveland, Ohio, USA. luri@medicon.cz
authors.forename: Lucie
authors.initials: L
authors.lastname: Riedlbauchová
authors.forename: Richard
authors.initials: R
authors.lastname: Brunken
authors.forename: Wael A
authors.initials: WA
authors.lastname: Jaber
authors.forename: Lucie
authors.initials: L
authors.lastname: Popová
authors.forename: Dimpi
authors.initials: D
authors.lastname: Patel
authors.forename: Vera
authors.initials: V
authors.lastname: Lánská
authors.forename: Kenneth
authors.initials: K
authors.lastname: Civello
authors.forename: Jennifer
authors.initials: J
authors.lastname: Cummings
authors.forename: J David
authors.initials: JD
authors.lastname: Burkhardt
authors.forename: Walid
authors.initials: W
authors.lastname: Saliba
authors.forename: David
authors.initials: D
authors.lastname: Martin
authors.forename: Robert
authors.initials: R
authors.lastname: Schweikert
authors.forename: Bruce L
authors.initials: BL
authors.lastname: Wilkoff
authors.forename: Richard
authors.initials: R
authors.lastname: Grimm
authors.forename: Andrea
authors.initials: A
authors.lastname: Natale
mesh_terms: D000368:Aged; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D009202:Cardiomyopathies / Q000175:diagnosis* / Q000517:prevention & control*; D005260:Female; D006801:Humans; D008297:Male; D017202:Myocardial Ischemia / Q000175:diagnosis* / Q000517:prevention & control*; D017682:Myocardial Stunning / Q000175:diagnosis* / Q000517:prevention & control*; D011379:Prognosis; D014022:Tissue Survival; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis* / Q000517:prevention & control*