title: Primary endpoints of the biventricular pacing after cardiac surgery trial.
abstract: BACKGROUND
  This study sought to determine whether optimized biventricular pacing increases cardiac index in patients at risk of left ventricular dysfunction after cardiopulmonary bypass. Procedures included coronary artery bypass, aortic or mitral surgery and combinations. This trial was approved by the Columbia University Institutional Review Board and was conducted under an Investigational Device Exemption.
  
  
  METHODS
  Screening of 6,346 patients yielded 47 endpoints. With informed consent, 61 patients were randomized to pacing or control groups. Atrioventricular and interventricular delays were optimized 1 (phase I), 2 (phase II), and 12 to 24 hours (phase III) after bypass in all patients. Cardiac index was measured by thermal dilution in triplicate. A 2-sample t test assessed differences between groups and subgroups.
  
  
  RESULTS
  Cardiac index was 12% higher (2.83±0.16 [standard error of the mean] vs 2.52±0.13 liters/minute/square meter) in the paced group, less than predicted and not statistically significant (p=0.14). However, when aortic and aortic-mitral surgery groups were combined, cardiac index increased 29% in the paced group (2.90±0.19, n=14) versus controls (2.24±0.15, n=11) (p=0.0138). Using a linear mixed effects model, t-test revealed that mean arterial pressure increased with pacing versus no pacing at all optimization points (phase I 79.2±1.7 vs 74.5±1.6 mm Hg, p=0.008; phase II 75.9±1.5 vs 73.6±1.8, p=0.006; phase III 81.9±2.8 vs 79.5±2.7, p=0.002).
  
  
  CONCLUSIONS
  Cardiac index did not increase significantly overall but increased 29% after aortic valve surgery. Mean arterial pressure increased with pacing at 3 time points. Additional studies are needed to distinguish rate from resynchronization effects, emphasize atrioventricular delay optimization, and examine clinical benefits of temporary postoperative pacing.
authors.affiliation: Department of Surgery, Columbia Presbyterian Medical Center, New York, New York 10032, USA. hms2@columbia.edu
authors.forename: Henry M
authors.initials: HM
authors.lastname: Spotnitz
authors.forename: Santos E
authors.initials: SE
authors.lastname: Cabreriza
authors.forename: Daniel Y
authors.initials: DY
authors.lastname: Wang
authors.forename: T Alexander
authors.initials: TA
authors.lastname: Quinn
authors.forename: Bin
authors.initials: B
authors.lastname: Cheng
authors.forename: Lauren N
authors.initials: LN
authors.lastname: Bedrosian
authors.forename: Linda
authors.initials: L
authors.lastname: Aponte-Patel
authors.forename: Craig R
authors.initials: CR
authors.lastname: Smith
mesh_terms: D000368:Aged; D062186:Arterial Pressure / Q000502:physiology; D058406:Cardiac Resynchronization Therapy / Q000379:methods* / Q000706:statistics & numerical data; D006348:Cardiac Surgical Procedures / Q000009:adverse effects / Q000379:methods*; D002315:Cardiopulmonary Bypass / Q000009:adverse effects / Q000379:methods; D001026:Coronary Artery Bypass / Q000009:adverse effects / Q000379:methods; D004452:Echocardiography / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006334:Heart Function Tests; D019918:Heart Valve Prosthesis Implantation / Q000379:methods; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D011182:Postoperative Care / Q000379:methods*; D012016:Reference Values; D018570:Risk Assessment; D013318:Stroke Volume / Q000502:physiology; D015996:Survival Rate; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging / Q000401:mortality / Q000503:physiopathology / Q000628:therapy*
keywords: 24