title: Cardiac resynchronization therapy and the relationship of percent biventricular pacing to symptoms and survival.
abstract: BACKGROUND
  With the advent of cardiac resynchronization therapy, it was unclear what percentage of biventricular pacing would be required to obtain maximal symptomatic and mortality benefit from the therapy. The optimal percentage of biventricular pacing and the association between the amount of continuous pacing and survival is unknown.
  
  
  OBJECTIVE
  The purpose of this study was to assess the optimal percentage of biventricular pacing and any association with survival in a large cohort of networked patients.
  
  
  METHODS
  A large cohort of 36,935 patients followed up in a remote-monitoring network, the LATITUDE Patient Management system (Boston Scientific Corp., Natick, Massachusetts), was assessed to determine the association between the percentage of biventricular pacing and mortality.
  
  
  RESULTS
  The greatest magnitude of reduction in mortality was observed with a biventricular pacing achieved in excess of 98% of all ventricular beats. Atrial fibrillation and native atrial ventricular condition can limit a high degree of biventricular pacing. Incremental increases in mortality benefit are observed with an increasing percentage of biventricular pacing.
  
  
  CONCLUSIONS
  Every effort should be made to reduce native atrioventricular conduction with cardiac resynchronization therapy systems in an attempt to achieve biventricular pacing as close to 100% as possible.
authors.affiliation: Mayo Clinic, Rochester, Minnesota 55905, USA. dhayes@mayo.edu
authors.forename: David L
authors.initials: DL
authors.lastname: Hayes
authors.forename: John P
authors.initials: JP
authors.lastname: Boehmer
authors.forename: John D
authors.initials: JD
authors.lastname: Day
authors.forename: F R
authors.initials: FR
authors.lastname: Gilliam
authors.forename: Paul A
authors.initials: PA
authors.lastname: Heidenreich
authors.forename: Milan
authors.initials: M
authors.lastname: Seth
authors.forename: Paul W
authors.initials: PW
authors.lastname: Jones
authors.forename: Leslie A
authors.initials: LA
authors.lastname: Saxon
mesh_terms: D000368:Aged; D002037:Bundle-Branch Block / Q000401:mortality / Q000628:therapy*; D002304:Cardiac Pacing, Artificial; D015331:Cohort Studies; D005260:Female; D006333:Heart Failure / Q000401:mortality / Q000628:therapy*; D006801:Humans; D008297:Male; D008404:Massachusetts; D018670:Monitoring, Ambulatory; D011358:Product Surveillance, Postmarketing; D012042:Registries; D012189:Retrospective Studies; D016019:Survival Analysis; D016896:Treatment Outcome; D014481:United States