title: Impact of viability and scar tissue on response to cardiac resynchronization therapy in ischaemic heart failure patients.
abstract: OBJECTIVE
  At present, 20-30% of patients do not respond to cardiac resynchronization therapy (CRT). In this study, the relation between the extent of viable myocardium and scar tissue vs. response to CRT was evaluated. In addition, the presence of scar tissue in the left ventricular (LV) lead position was specifically related to response to CRT.
  
  
  RESULTS
  A total of 51 consecutive patients with ischaemic heart failure and substantial LV dyssynchrony undergoing CRT were included. All patients underwent gated SPECT before CRT implantation to determine the extent of scar tissue and viable myocardium. Clinical and echocardiographic parameters were assessed at baseline and after 6 months of CRT. The results demonstrated direct relations between the response to CRT and the extent of viable myocardium and scar tissue. In addition, the 15 patients (29%) with transmural scar tissue (< 50% tracer activity) in the region of the LV pacing lead showed no improvement after 6 months of CRT.
  
  
  CONCLUSIONS
  The extent of scar tissue and viable myocardium were directly related to the response to CRT. Furthermore, scar tissue in the LV pacing lead region may prohibit response to CRT. Evaluation for viability and scar tissue may be considered in the selection process for CRT.
authors.affiliation: Department of Cardiology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, the Netherlands.
authors.forename: Claudia
authors.initials: C
authors.lastname: Ypenburg
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Schalij
authors.forename: Gabe B
authors.initials: GB
authors.lastname: Bleeker
authors.forename: Paul
authors.initials: P
authors.lastname: Steendijk
authors.forename: Eric
authors.initials: E
authors.lastname: Boersma
authors.forename: Petra
authors.initials: P
authors.lastname: Dibbets-Schneider
authors.forename: Marcel P M
authors.initials: MP
authors.lastname: Stokkel
authors.forename: Ernst E
authors.initials: EE
authors.lastname: van der Wall
authors.forename: Jeroen J
authors.initials: JJ
authors.lastname: Bax
mesh_terms: D000368:Aged; D002304:Cardiac Pacing, Artificial; D002921:Cicatrix / Q000473:pathology* / Q000503:physiopathology; D004562:Electrocardiography; D005260:Female; D006333:Heart Failure / Q000473:pathology* / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D008297:Male; D017202:Myocardial Ischemia / Q000473:pathology* / Q000503:physiopathology; D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D015899:Tomography, Emission-Computed, Single-Photon; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000473:pathology* / Q000503:physiopathology
chemical_list: D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C078700:technetium tc-99m tetrofosmin