title: Long-term outcome of cardiac resynchronization therapy in patients with severe congestive heart failure.
abstract: BACKGROUND
  Cardiac resynchronization therapy (CRT) has recently been shown to be an effective short-term therapy for patients with drug-refractory heart failure and intraventricular conduction delay. Little is known about the long-term effects of this therapy.
  
  
  OBJECTIVE
  To determine the long-term outcome of all consecutive patients who underwent CRT at two Canadian centres, and to determine what baseline variables predict a response to CRT.
  
  
  CONCLUSIONS
  The present study comprised a total of 85 patients (mean age 66+/-9 years; 88% male) with New York Heart Association class II (4%), class III (84%) or class IV (12%) heart failure. All patients fulfilled the standard CRT indications with a QRS duration of 168+/-22 ms and a nuclear gated ejection fraction (EF) of 21+/-6%. Eighteen of the 85 patients were implanted with a combination automatic implantable cardioverter-defibrillator and CRT device. Within a mean clinical follow-up of 3.0+/-1.0 years, 26 of the 85 patients died, and eight patients underwent cardiac transplantation, with four transplant-related deaths (mean survival 3.53+/-0.26 years). Ten patients died of sudden cardiac death, eight patients died of progressive heart failure and eight patients died of noncardiac causes. None of the baseline factors (age, sex, EF, etiology, New York Heart Association class, QRS duration or implantable cardioverter-defibrillator) or indexes of CRT (change in EF or QRS duration) were predictive of a poor outcome. There was a clear trend for patients with a greater left ventricular EF gain to have a better outcome (P=0.1). The present observational data represent one of the longest follow-up databases of patients undergoing CRT. The significant morbidity and mortality found after CRT highlight the severity of the underlying cardiac pathology and concurrent illnesses.
authors.affiliation: Division of Cardiology, University of Ottawa Heart Institute, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Darryl R
authors.initials: DR
authors.lastname: Davis
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Krahn
authors.forename: Anthony S L
authors.initials: AS
authors.lastname: Tang
authors.forename: Robert
authors.initials: R
authors.lastname: Lemery
authors.forename: Martin S
authors.initials: MS
authors.lastname: Green
authors.forename: Michael
authors.initials: M
authors.lastname: Gollob
authors.forename: Raymond
authors.initials: R
authors.lastname: Yee
authors.forename: Allan C
authors.initials: AC
authors.lastname: Skanes
authors.forename: George J
authors.initials: GJ
authors.lastname: Klein
authors.forename: David H
authors.initials: DH
authors.lastname: Birnie
mesh_terms: D000368:Aged; D016757:Death, Sudden, Cardiac; D017147:Defibrillators, Implantable; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000401:mortality* / Q000503:physiopathology / Q000628:therapy*; D016027:Heart Transplantation / Q000401:mortality; D006801:Humans; D008297:Male; D009864:Ontario / Q000453:epidemiology; D017063:Outcome Assessment, Health Care; D010138:Pacemaker, Artificial; D013318:Stroke Volume / Q000502:physiology