title: Effects of AV delay and VV delay on left atrial pressure and waveform in ambulant heart failure patients: insights into CRT optimization.
abstract: BACKGROUND
  We hypothesized that left atrial pressure (LAP) obtained by a permanent implantable sensor is sensitive to changes in cardiac resynchronization therapy (CRT) settings and could guide CRT optimization to improve the response rate. We investigated the effect of CRT optimization on LAP and its waveform parameters in ambulant heart failure (HF) patients.
  
  
  METHODS
  CRT optimization was performed in eight ambulant HF patients, using echocardiography as reference. LAP waveform was acquired at each of eight atrioventricular (AV) intervals and five inter-ventricular (VV) intervals. Selected waveform parameters were also evaluated for their sensitivity to CRT changes and agreement with echocardiography-guided optimal settings.
  
  
  RESULTS
  Optimal AV and VV intervals varied considerably between patients. All patients exhibited significant changes in waveform morphology with AV optimization. Optimal AV delay determined from echocardiography ranged between 140 ms and 225 ms. Mean LAP tended to be lower at optimal setting 14 ± 3 mmHg compared to shorter (<100 ms) or longer (>160 ms) AV settings (P = 0.16). There were clear trends to smaller peak a-wave (P = 0.11) and gentler positive a-slope (P = 0.15) and positive v-slope (P = 0.09) with longer AV delays. Mean LAP and negative v-wave slope correlated well with echo-guided optimal setting, r = 0.91 (P = 0.001) and 0.79 (P = 0.03), respectively. No significant effects on LAP or waveform were seen during VV optimization.
  
  
  CONCLUSIONS
  LAP and its waveform changes considerably with AV optimization. There is good agreement between echo-guided optimal setting and LAP. LAP could provide an objective guide to CRT optimization. (Clinical Trial Registry information: URL: http://www.clinicaltrials.gov. Unique Identifier: NCT00632372).
authors: Cardiology Department, Christchurch Hospital, Christchurch, New Zealand.
authors: W Y Wandy
authors: WY
authors: Chan
authors: Andreas
authors: A
authors: Blomqvist
authors: Iain C
authors: IC
authors: Melton
authors: Kjell
authors: K
authors: Norén
authors: Ian G
authors: IG
authors: Crozier
authors: Michael E
authors: ME
authors: Benser
authors: Neal L
authors: NL
authors: Eigler
authors: Dan
authors: D
authors: Gutfinger
authors: Richard W
authors: RW
authors: Troughton
mesh_terms: D000328:Adult; D000368:Aged; D062185:Atrial Pressure; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D005240:Feasibility Studies; D006333:Heart Failure / Q000503:physiopathology* / Q000628:therapy*; D006801:Humans; D008875:Middle Aged; D011446:Prospective Studies
keywords: cadiac resynchronization therapy; heart failure; left atrial pressure