title: Improvement in Clinical Outcomes With Biventricular Versus Right Ventricular Pacing: The BLOCK HF Study.
abstract: BACKGROUND
  Sustained right ventricular (RV) apical pacing may lead to deterioration in ventricular function and an increased risk of heart failure, especially in patients with pre-existing systolic dysfunction. The BLOCK HF (Biventricular Versus Right Ventricular Pacing in Heart Failure Patients With Atrioventricular Block) trial demonstrated that biventricular-paced patients had a reduced incidence of a composite endpoint of death, heart failure-related urgent care, and adverse left ventricular remodeling.
  
  
  OBJECTIVE
  In a pre-specified analysis, this study examined clinical outcomes, including clinical composite score, quality of life (QOL), and change in New York Heart Association (NYHA) functional classification.
  
  
  METHODS
  The BLOCK HF trial randomized patients with atrioventricular block, NYHA symptom class I to III heart failure, and left ventricular ejection fraction ≤50% to biventricular or RV pacing. NYHA functional classification, QOL, and clinical composite score were assessed at 6, 12, 18, and 24 months. Bayesian statistical methods were used, with the pre-specified metric of benefit being a posterior probability ≥0.95.
  
  
  RESULTS
  Patients with biventricular pacing showed greater improvement in NYHA functional class at 12 months, with 19% improved, 61% unchanged, and 17% worsened, compared with 12%/62%/23% in the RV arm. QOL was improved through 12 months. At 6 months, clinical composite score was improved/unchanged/worsened in 53%/24%/24% in the biventricular arm compared with 39%/33%/28% in the RV arm. This improvement in clinical composite score was sustained through 24 months.
  
  
  CONCLUSIONS
  For patients with atrioventricular block and systolic dysfunction, biventricular pacing not only reduces the risk of mortality/morbidity, but also leads to better clinical outcomes, including improved QOL and heart failure status, compared with RV pacing. (Biventricular Versus Right Ventricular Pacing in Heart Failure Patients With Atrioventricular Block [BLOCK HF]; NCT00267098).
authors.affiliation: Department of Medicine, University at Buffalo, Buffalo, New York. Electronic address: abcurtis@buffalo.edu.
authors.forename: Anne B
authors.initials: AB
authors.lastname: Curtis
authors.affiliation: The Heart Group, Lancaster General Health, Lancaster, Pennsylvania.
authors.forename: Seth J
authors.initials: SJ
authors.lastname: Worley
authors.affiliation: Ohio Heart and Vascular, The Christ Hospital Health Network, Cincinnati, Ohio.
authors.forename: Eugene S
authors.initials: ES
authors.lastname: Chung
authors.affiliation: Medtronic, PLC, Mounds View, Minnesota.
authors.forename: Pei
authors.initials: P
authors.lastname: Li
authors.affiliation: Medtronic, PLC, Mounds View, Minnesota.
authors.forename: Shelly A
authors.initials: SA
authors.lastname: Christman
authors.affiliation: Cardiovascular Medicine Division, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Martin
authors.initials: M
authors.lastname: St John Sutton
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D054537:Atrioventricular Block / Q000628:therapy*; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D017147:Defibrillators, Implantable; D004311:Double-Blind Method; D005260:Female; D054143:Heart Failure, Systolic / Q000145:classification / Q000628:therapy*; D006801:Humans; D008297:Male; D010138:Pacemaker, Artificial; D011446:Prospective Studies; D011788:Quality of Life
keywords: atrioventricular block; biventricular pacing; cardiac resynchronization therapy; heart failure; quality of life