title: Assessment of resynchronization therapy on functional status and quality of life in patients requiring an implantable defibrillator.
abstract: BACKGROUND
  The effect of cardiac resynchronization therapy (CRT) on physical function and Quality of Life (QoL) in patients who require an implantable defibrillator but do not meet guideline criteria for CRT has not been studied in detail.
  
  
  RESULTS
  This was a randomized study of 72 patients with high risk of sudden cardiac death, ejection fraction (EF) < or =35%, mild-to-moderate heart failure symptoms, and QRS > 120 ms. Patients received a CRT defibrillator and were randomized to CRT turned ON or OFF. Objective and subjective measures were performed at baseline and after 6 months. There was no difference in change in left ventricular end-systolic volume (ESV) by radionuclid angiogram scan, the primary endpoint, between the CRT ON group (DeltaESV =-7 +/- 52 mL), and CRT OFF group (DeltaESV =-30 +/- 47 mL). Similarly, echocardiogram measures of ESV and EF showed no difference between the two groups. In the CRT ON group, selected measures of QoL and subjective exercise tolerance but not heart failure symptoms improved significantly. Six-minute walk distance prolonged in the CRT ON group (baseline 313.6 +/- 114.4 m, 6-month 365.0 +/- 122.5 m, P = 0.01), but the difference in change in walk distance between the two groups was not significant.
  
  
  CONCLUSIONS
  Further studies with larger sample size and longer follow-up will be required to allow definite conclusions regarding the potential benefit of CRT in this patient population.
authors.affiliation: Department of Medicine, Division of Cardiology, University of Toronto, St. Michael's Hospital, Toronto, Ontario, Canada.
authors.forename: Arnold
authors.initials: A
authors.lastname: Pinter
authors.forename: Iqwal
authors.initials: I
authors.lastname: Mangat
authors.forename: Victoria
authors.initials: V
authors.lastname: Korley
authors.forename: Stuart
authors.initials: S
authors.lastname: Connolly
authors.forename: Sean
authors.initials: S
authors.lastname: Connors
authors.forename: Martin
authors.initials: M
authors.lastname: Gardner
authors.forename: Francois
authors.initials: F
authors.lastname: Philippon
authors.forename: Larry
authors.initials: L
authors.lastname: Sterns
authors.forename: Bernard
authors.initials: B
authors.lastname: Thibault
authors.forename: Paul
authors.initials: P
authors.lastname: Dorian
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002304:Cardiac Pacing, Artificial; D017147:Defibrillators, Implantable; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D015637:Gated Blood-Pool Imaging; D006333:Heart Failure / Q000503:physiopathology* / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011788:Quality of Life