title: Cardiac resynchronization therapy optimization using noninvasive cardiac output measurement.
abstract: OBJECTIVE
  Noninvasive cardiac output (CO) measurement (NICOM) is a novel method to assess ventricular function and offers a potential alternative for optimization of cardiac resynchronization therapy (CRT) devices. We compared the effect of NICOM-based optimization to no optimization (empiric settings) on CRT outcomes.
  
  
  METHODS
  Two hundred and three patients undergoing CRT were assessed in two consecutive nonrandomized groups; an empiric group (n = 54) was programmed to "out of the box" settings with a fixed AV delay of 120 ms and a VV delay of 0 ms; and the optimization group (n = 149) underwent adjustments of both the AV and VV delays according to the greatest improvement in resting CO. The primary endpoints were improvements in left ventricular (LV) volumes and function from baseline at 6 months. Secondary endpoints were change in New York Heart Association (NYHA) class, quality of life score, and 6-minute walk test (6 MWT) performance.
  
  
  RESULTS
  After 6 months of CRT, the optimization group had a better clinical response with lower NYHA class (2.1 ± 0.8 vs 2.4 ± 0.8, P = 0.048) and quality of life scores (35 ± 18 vs 42 ± 20, P = 0.045) but no differences in 6-MWT performance (269 ± 110 vs 277 ± 114 m, P = 0.81). Echocardiographic response was also better in the optimization group with lower LV end systolic volume (108 ± 51 vs 126 ± 60 mL, P = 0.048) and higher ejection fraction (30 ± 7 vs 27 ± 8, P = 0.01) compared to empiric settings.
  
  
  CONCLUSIONS
  Device optimization using noninvasive measures of CO is associated with better clinical and echocardiographic response compared to empiric settings.
authors.affiliation: Department of Cardiovascular Medicine, Addenbrooke’s Hospital, Cambridge, UK.
authors.forename: Fakhar Z
authors.initials: FZ
authors.lastname: Khan
authors.forename: Munmohan S
authors.initials: MS
authors.lastname: Virdee
authors.forename: John
authors.initials: J
authors.lastname: Hutchinson
authors.forename: Beverley
authors.initials: B
authors.lastname: Smith
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Pugh
authors.forename: Philip A
authors.initials: PA
authors.lastname: Read
authors.forename: Simon P
authors.initials: SP
authors.lastname: Fynn
authors.forename: David P
authors.initials: DP
authors.lastname: Dutka
mesh_terms: D000368:Aged; D002302:Cardiac Output; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D002307:Cardiography, Impedance / Q000379:methods*; D005260:Female; D006333:Heart Failure / Q000150:complications / Q000175:diagnosis* / Q000517:prevention & control*; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000150:complications / Q000175:diagnosis* / Q000517:prevention & control*