title: Atrioventricular delay programming and the benefit of cardiac resynchronization therapy in MADIT-CRT.
abstract: BACKGROUND
  The optimal atrioventricular pacing delay (AVD) in cardiac resynchronization therapy (CRT) remains to be determined.
  
  
  OBJECTIVE
  To determine whether programming CRT devices to short AVD (S-AVD) will improve clinical response secondary to greater reductions in dyssynchrony.
  
  
  METHODS
  The study population comprised 1235 patients with left bundle branch block enrolled in Multicenter Automatic Defibrillator Implantation Trial in Cardiac Resynchronization Therapy (MADIT-CRT). We assessed the relationship between AVD and outcomes. Patients programmed to S-AVD (median value of <120 ms; n = 337) vs long AVD (L-AVD; ≥120 ms; n = 390) were assessed for the end points of heart failure (HF) or death, death alone, and echocardiographic response to the CRT at 1-year follow-up. Outcomes were also compared to the left bundle branch block implantable cardioverter-defibrillator-only group (n = 508).
  
  
  RESULTS
  Multivariate analysis showed that patients programmed to S-AVD experienced a significant 33% (hazard ratio [HR] 0.67; 95% confidence interval [CI] 0.44-0.85; P = .037) reduction in the risk of HF or death and a 47% (HR 0.53; 95% CI 0.29-0.94; P = .031) reduction in death alone as compared with those programmed to L-AVD. Patients with CRT-programmed S-AVD and L-AVD experienced 63% (HR 0.37; 95% CI 0.26-0.53; P < .001) and 46% (HR 0.54; 95% CI 0.31-0.96; P < .001) reduction, respectively, in the risk of HF or death compared to patients with implantable cardioverter-defibrillator alone. At 1 year of follow-up, S-AVD vs L-AVD was associated with a greater reduction in left ventricular end-systolic volume (34.2% vs 30.8%; P = .002) along with a significantly greater improvement in dyssynchrony (22.3% vs 9.4%; P = .036).
  
  
  CONCLUSIONS
  Our findings indicate that in MADIT-CRT programming, the CRT AVD <120 ms was associated with a greater clinical and echocardiographic response to CRT.
authors.affiliation: Cardiology Division, Department of Medicine, University of Rochester Medical Center, Rochester, New York, USA. Andrew_Brenyo@urmc.rochester.edu
authors.forename: Andrew
authors.initials: A
authors.lastname: Brenyo
authors.forename: Valentina
authors.initials: V
authors.lastname: Kutyifa
authors.forename: Arthur J
authors.initials: AJ
authors.lastname: Moss
authors.forename: Andrew
authors.initials: A
authors.lastname: Mathias
authors.forename: Alon
authors.initials: A
authors.lastname: Barsheshet
authors.forename: Anne-Catherine
authors.initials: AC
authors.lastname: Pouleur
authors.forename: Dorit
authors.initials: D
authors.lastname: Knappe
authors.forename: Scott
authors.initials: S
authors.lastname: McNitt
authors.forename: Bronislava
authors.initials: B
authors.lastname: Polonsky
authors.forename: David T
authors.initials: DT
authors.lastname: Huang
authors.forename: Scott D
authors.initials: SD
authors.lastname: Solomon
authors.forename: Wojciech
authors.initials: W
authors.lastname: Zareba
authors.forename: Ilan
authors.initials: I
authors.lastname: Goldenberg
mesh_terms: D000368:Aged; D002037:Bundle-Branch Block / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000628:therapy*; D002170:Canada; D058406:Cardiac Resynchronization Therapy / Q000009:adverse effects / Q000379:methods* / Q000401:mortality; D004452:Echocardiography; D005060:Europe; D005260:Female; D006333:Heart Failure / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016019:Survival Analysis; D016896:Treatment Outcome; D014481:United States
keywords: AVD; Atrioventricular delay; CI; CRT-D; Cardiac resynchronization therapy; HF; HR; Heart failure; ICD; IQR; L-AVD; LBBB; LV; LVEDV; LVESV; MADIT-CRT; Multicenter Automatic Defibrillator Implantation Trial in Cardiac Resynchronization Therapy; NYHA; New York Heart Association; S-AVD; SMART-AV; Smart Delay determined AV optimization: A comparison of AV optimization methods used in cardiac resynchronization therapy; atrioventricular delay; cardiac resynchronization therapy-defibrillator; confidence interval; hazard ratio; heart failure; implantable cardioverter-defibrillator; interquartile range; left bundle branch block; left ventricle/ventricular; left ventricular end-diastolic volume; left ventricular end-systolic volume; long AVD; short AVD