title: Cardiac resynchronization with sequential biventricular pacing for the treatment of moderate-to-severe heart failure.
abstract: OBJECTIVE
  The InSync III study evaluated sequential cardiac resynchronization therapy (CRT) in patients with moderate-to-severe heart failure and prolonged QRS.
  
  
  BACKGROUND
  Simultaneous CRT improves hemodynamic and clinical performance in patients with moderate-to-severe heart failure (HF) and a wide QRS. Recent evidence suggests that sequentially stimulating the ventricles might provide additional benefit.
  
  
  METHODS
  This multicenter, prospective, nonrandomized, six-month trial enrolled a total of 422 patients to determine the effectiveness of sequential CRT in patients with New York Heart Association (NYHA) functional class III or IV HF and a prolonged QRS. The study evaluated: whether patients receiving sequential CRT for six months experienced improvement in 6-min hall walk (6MHW) distance, NYHA functional class, and quality of life (QoL) over control group patients from the reported Multicenter InSync Randomized Clinical Evaluation (MIRACLE) trial; whether sequential CRT increased stroke volume compared to simultaneous CRT; and whether an increase in stroke volume translated into greater clinical improvements compared to patients receiving simultaneous CRT.
  
  
  RESULTS
  InSync III patients experienced greater improvement in 6MHW, NYHA functional class, and QoL at six months compared to control (all p < 0.0001). Optimization of the sequential pacing increased (median 7.3%) stroke volume in 77% of patients. No additional improvement in NYHA functional class or QoL was seen compared to the simultaneous CRT group; however, InSync III patients demonstrated greater exercise capacity.
  
  
  CONCLUSIONS
  Sequential CRT provided most patients with a modest increase in stroke volume above that achieved during simultaneous CRT. Patients receiving sequential CRT had improved exercise capacity, but no change in functional status or QoL.
authors.affiliation: Carlyle Fraser Heart Center/Division of Cardiology, Emory University, Atlanta, Georgia, USA. angel_leon@emoryhealthcare.org
authors.forename: Angel R
authors.initials: AR
authors.lastname: León
authors.forename: William T
authors.initials: WT
authors.lastname: Abraham
authors.forename: Susan
authors.initials: S
authors.lastname: Brozena
authors.forename: James P
authors.initials: JP
authors.lastname: Daubert
authors.forename: Westby G
authors.initials: WG
authors.lastname: Fisher
authors.forename: John C
authors.initials: JC
authors.lastname: Gurley
authors.forename: Chang Seng
authors.initials: CS
authors.lastname: Liang
authors.forename: George
authors.initials: G
authors.lastname: Wong
mesh_terms: D000368:Aged; D002303:Cardiac Output, Low / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy*; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D004562:Electrocardiography; D005260:Female; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D011788:Quality of Life; D012720:Severity of Illness Index; D013997:Time Factors; D016896:Treatment Outcome; D016138:Walking