title: Whether noninvasive optimization of AV and VV delays improves the response to cardiac resynchronization therapy.
abstract: BACKGROUND
  Device optimization is not routinely performed in patients who underwent cardiac resynchronization therapy (CRT) device implantation. Noninvasive optimization of CRT devices by measurement of cardiac output (CO) can be used as a simple method to assess ventricular systolic performance. The aim of this study was to assess whether optimization of atrioventricular (AV) and interventricular (VV) delay can improve hemodynamic response to CRT and whether this optimization should be performed for each patient individually.
  
  
  METHODS
  Twenty patients with advanced heart failure New York Heart Association (NYHA) class III/IV, left ventricular ejection fraction ≤ 35% and left bundle branch block (QRS ≥ 120 ms) in sinus rhythm were evaluated from 24 h to 48 h after implantation of a CRT device by means of impedance cardiography (ICG). CO was first measured at each patient's intrinsic rhythm. Patients then underwent adjustments of AV and VV delay from 80 ms to 140 ms and from -60 ms to +60 ms, respectively in 20 ms increment steps and CO at each setting was measured by ICG. Both AV and VV delays were programmed according to the greatest improvement in CO compared to intrinsic rhythm.
  
  
  RESULTS
  There was a statistically signifi cant increase in CO measured at the intrinsic rhythm compared to different AV delay by mean of 21% (3.8 ± 1.0 vs. 4.6 ± 0.1 L/min, p < 0.05). Optimal AV/VV delays with left ventricle-preexcitation or simultaneous biventricular pacing caused additional increased CO from intrinsic rhythm by mean of 32.6% (3.8 ± 1.0 vs. 5.04 ± ± 1.0 L/min, p < 0.05). Optimal AV/VV setting delays also resulted in improved hemodynamic responses compared to VV factory setting delay.
  
  
  CONCLUSIONS
  Both AV and VV delay optimization should be performed in clinical practice. Optimal AV delay improved outcome. However, combination of optimized AV/VV delays provided the best hemodynamic response. Optimized AV/VV delays with left ventricle-preexcitation or simultaneous biventricular pacing increased hemodynamic output compared to intrinsic rhythm and VV factory setting delay.
authors.affiliation: Department of Electrocardiology, Medical University of Lodz, Lodz, Poland. bozena_urbanek@op.pl.
authors.forename: Bożena
authors.initials: B
authors.lastname: Urbanek
authors.forename: Michał
authors.initials: M
authors.lastname: Chudzik
authors.forename: Artur
authors.initials: A
authors.lastname: Klimczak
authors.forename: Marcin
authors.initials: M
authors.lastname: Rosiak
authors.forename: Joanna
authors.initials: J
authors.lastname: Lewek
authors.forename: Jerzy Krzysztof
authors.initials: JK
authors.lastname: Wranicz
mesh_terms: D000368:Aged; D001283:Atrioventricular Node / Q000503:physiopathology*; D002037:Bundle-Branch Block / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D058406:Cardiac Resynchronization Therapy; D058409:Cardiac Resynchronization Therapy Devices; D002307:Cardiography, Impedance; D004867:Equipment Design; D006333:Heart Failure / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013318:Stroke Volume; D013997:Time Factors; D016896:Treatment Outcome; D016277:Ventricular Function, Left