title: Comparison of different invasive hemodynamic methods for AV delay optimization in patients with cardiac resynchronization therapy: implications for clinical trial design and clinical practice.
abstract: BACKGROUND
  Reproducibility and hemodynamic efficacy of optimization of AV delay (AVD) of cardiac resynchronization therapy (CRT) using invasive LV dp/dtmax are unknown.
  
  
  RESULTS
  25 patients underwent AV delay (AVD) optimisation twice, using continuous left ventricular (LV) dp/dtmax, systolic blood pressure (SBP) and pulse pressure (PP). We compared 4 protocols for comparing dp/dtmax between AV delays: We assessed for dp/dtmax, LVSBP and LVPP, test-retest reproducibility of the optimum. Optimization using immediate absolute dp/dtmax had poor reproducibility (SDD of replicate optima=41 ms; R(2)=0.45) as did delayed absolute (SDD 39 ms; R(2)=0.50). Multiple relative had better reproducibility: SDD 23 ms, R(2)=0.76, and (p<0.01 by F test). Compared with AAI pacing, the hemodynamic increment from CRT, with the nominal AV delay was LVSBP 2% and LVdp/dtmax 5%, while CRT with pre-determined optimal AVD gave 6% and 9% respectively.
  
  
  CONCLUSIONS
  Because of inevitable background fluctuations, optimization by absolute dp/dtmax has poor same-day reproducibility, unsuitable for clinical or research purposes. Reproducibility is improved by comparing to a reference AVD and making multiple consecutive measurements. More than 6 measurements would be required for even more precise optimization--and might be advisable for future study designs. With optimal AVD, instead of nominal, the hemodynamic increment of CRT is approximately doubled.
authors.affiliation: Hôpital du Haut-Lévèque, Pessac, France; International Centre for Circulatory Health, National Heart and Lung Institute, Imperial College London, UK. Electronic address: z.whinnett@imperial.ac.uk.
authors.forename: Zachary I
authors.initials: ZI
authors.lastname: Whinnett
authors.forename: Darrel P
authors.initials: DP
authors.lastname: Francis
authors.forename: Arnaud
authors.initials: A
authors.lastname: Denis
authors.forename: Keith
authors.initials: K
authors.lastname: Willson
authors.forename: Patrizio
authors.initials: P
authors.lastname: Pascale
authors.forename: Irene
authors.initials: I
authors.lastname: van Geldorp
authors.forename: Maxime
authors.initials: M
authors.lastname: De Guillebon
authors.forename: Sylvain
authors.initials: S
authors.lastname: Ploux
authors.forename: Kenneth
authors.initials: K
authors.lastname: Ellenbogen
authors.forename: Michel
authors.initials: M
authors.lastname: Haïssaguerre
authors.forename: Philippe
authors.initials: P
authors.lastname: Ritter
authors.forename: Pierre
authors.initials: P
authors.lastname: Bordachar
mesh_terms: D000328:Adult; D000368:Aged; D001283:Atrioventricular Node / Q000503:physiopathology*; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000503:physiopathology / Q000628:therapy*; D006352:Heart Ventricles / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D016896:Treatment Outcome; D016277:Ventricular Function, Left / Q000502:physiology*
keywords: Atrioventricular delay optimization; Biventricular pacing; Cardiac resynchronization therapy; Hemodynamic optimization; Reproducibility