title: Extending the boundaries of cardiac resynchronization therapy: efficacy in atrial fibrillation, New York heart association class II, and narrow QRS heart failure patients.
abstract: BACKGROUND
  Large-scale clinical trials have demonstrated the benefits of cardiac resynchronization therapy (CRT) in patients with New York Heart Association (NYHA) Class III/IV heart failure, systolic left ventricular dysfunction, and a wide QRS. However, additional patient groups may also benefit from CRT.
  
  
  RESULTS
  We meta-analyzed clinical benefits of CRT in heart failure patients with narrow QRS, atrial fibrillation (AF) and NYHA Class II symptoms. Thirteen trials of 2882 patients contributed to this meta-analysis. In the narrow versus wide QRS group comparison, no difference in benefit was observed for change in left ventricular ejection fraction (standardized mean difference [SMD] 0.30, 95% confidence interval [CI] -0.37 to 0.97) or left ventricular end systolic volume (SMD 0.30, 95% CI -1.14 to 1.74). The benefit was greater in the wide QRS group for the 6-minute walk test (SMD 1.27, 95% CI 0.59 to 1.96) and NYHA class improvement (SMD 1.24, 95% CI 0.72 to 1.75). In the atrial fibrillation (AF) versus sinus rhythm (SR) group comparison, no difference in benefit was observed for change in left ventricular ejection fraction (SMD -0.38, 95% CI -1.28 to 0.53) or NYHA improvement (SMD 0.32, 95% CI -0.77 to 1.40). In the NYHA II versus NYHA III/IV group comparison, no difference in benefit was observed for change in left ventricular end diastolic diameter (SMD 0.05, 95% CI -0.94 to 1.05) or left ventricular end systolic diameter (SMD 0.74, 95% CI -1.98 to 3.46).
  
  
  CONCLUSIONS
  Large-scale clinical outcome trials of CRT are warranted in heart failure patients with narrow QRS, AF, and NYHA II, given the similar benefits observed to those with wide QRS, SR, and NYHA III/IV for many parameters.
authors.affiliation: Alfred Hospital, Melbourne, Australia.
authors.forename: Sara
authors.initials: S
authors.lastname: Wein
authors.forename: Aleksandr
authors.initials: A
authors.lastname: Voskoboinik
authors.forename: Lironne
authors.initials: L
authors.lastname: Wein
authors.forename: Baki
authors.initials: B
authors.lastname: Billah
authors.forename: Henry
authors.initials: H
authors.lastname: Krum
mesh_terms: D001281:Atrial Fibrillation / Q000473:pathology / Q000628:therapy*; D002304:Cardiac Pacing, Artificial; D016001:Confidence Intervals; D005080:Exercise Test; D017079:Exercise Tolerance; D006333:Heart Failure / Q000473:pathology / Q000628:therapy*; D006801:Humans; D013318:Stroke Volume; D018487:Ventricular Dysfunction, Left / Q000628:therapy; D016277:Ventricular Function, Left