title: Cardiac resynchronisation therapy: pacemaker versus internal cardioverter-defibrillator in patients with impaired left ventricular function.
abstract: OBJECTIVE
  Studies have shown beneficial effects of cardiac resynchronisation therapy (CRT) on mortality among patients with heart failure. However the incremental benefits in survival from CRT with a defibrillator (CRT-D) are unclear. The choice of appropriate device remains unanswered.
  
  
  METHODS
  This is a single-centre observational study in a tertiary cardiac centre. Patients (n=500) implanted with a CRT device with pacing alone (CRT-P) (n=354) and CRT-D (n=146) were followed for at least 2 years (mean 29 months, SD 14 months). The primary end point was all-cause mortality.
  
  
  RESULTS
  A total of 116 deaths (23.2%) were recorded: 88 (24.8%) and 28 (19.2%), in the CRT-P and CRT-D groups, respectively. At 1 year there was a trend favouring CRT-D (HR 0.54, 95% CI 0.27 to 1.07, p=0.08) but this was attenuated by the 2nd year and became insignificant at the end of follow-up (HR 0.76, 95% CI 0.50 to 1.170, p=0.21). There was no survival benefit from having an internal cardioverter-defibrillator if patients were deemed non-responders to CRT. 27% of the CRT-P patients with ischaemic cardiomyopathy met indications for potential internal cardioverter-defibrillator implantation for primary prevention. These were older patients with poorer baseline function in comparison with CRT-D patients with devices for primary prevention. Once these differences were adjusted for, there was no difference in outcome between the groups.
  
  
  CONCLUSIONS
  CRT-D did not offer additional survival advantage over CRT-P at longer-term follow-up, as the clinical benefit of a defibrillator attenuated with time. Further work is needed to define which subset of patients benefit from CRT-D.
authors.affiliation: Papworth Hospital NHS Foundation Trust, , Cambridge, UK.
authors.forename: Khang-Li
authors.initials: KL
authors.lastname: Looi
authors.forename: Parag R
authors.initials: PR
authors.lastname: Gajendragadkar
authors.forename: Fakhar Z
authors.initials: FZ
authors.lastname: Khan
authors.forename: Maros
authors.initials: M
authors.lastname: Elsik
authors.forename: David A
authors.initials: DA
authors.lastname: Begley
authors.forename: Simon P
authors.initials: SP
authors.lastname: Fynn
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Grace
authors.forename: Patrick M
authors.initials: PM
authors.lastname: Heck
authors.forename: Munmohan
authors.initials: M
authors.lastname: Virdee
authors.forename: Sharad
authors.initials: S
authors.lastname: Agarwal
mesh_terms: D000368:Aged; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D017147:Defibrillators, Implantable; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000401:mortality / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D008297:Male; D010138:Pacemaker, Artificial; D012189:Retrospective Studies; D015996:Survival Rate / Q000639:trends; D013997:Time Factors; D016896:Treatment Outcome; D006113:United Kingdom / Q000453:epidemiology; D016277:Ventricular Function, Left / Q000502:physiology*