title: Endothelial dysfunction in heart failure identifies responders to cardiac resynchronization therapy.
abstract: BACKGROUND
  The presence of endothelial dysfunction is associated with increased heart failure mortality. Cardiac resynchronization therapy (CRT) improves heart failure outcomes; however, current guidelines do not adequately identify responders to CRT.
  
  
  OBJECTIVE
  The purpose of this study was to determine whether endothelial dysfunction can predict response to CRT.
  
  
  METHODS
  Brachial artery flow-mediated dilation, a measure of endothelial function, was measured at baseline preimplant and 90 days postimplant in 33 patients undergoing CRT (age 64.2 +/- 16.8 years, left ventricular ejection fraction [LVEF] 25% +/- 9%, QRS duration 158 +/- 25 ms, New York Heart Association class III-IV).
  
  
  RESULTS
  Of the 33 patients, 19 (58%) were responders to CRT. Baseline flow-mediated dilation was 4.6% +/- 4.5% in responders and 8.6% +/- 4.2% in nonresponders (P <.01). After 90 days of CRT, responders had significant improvement in LVEF (23% +/- 8% to 30% +/- 9%, P = .03), 6-minute walk distance (756 +/- 213 feet to 1,089 +/- 242 feet, P = .04), and quality of life (52 +/- 22 to 31 +/- 28, P <.005), whereas nonresponders did not show improvement in these measures. The presence of baseline endothelial dysfunction correlated with impaired baseline functional capacity (r = 0.39, P = .03), and improvement in flow-mediated dilation correlated with improvement in 6-minute walk distance (r = 0.34, P = .05). Logistic regression analysis showed that every 1% reduction in baseline flow-mediated dilation correlated with an approximately 5% increased likelihood of response to CRT. The predictive value of baseline endothelial dysfunction was independent of QRS duration, LVEF, or dyssynchrony and provided additive prognostic value.
  
  
  CONCLUSIONS
  The presence of endothelial dysfunction independently identifies CRT responders and provides additive prognostic value for predicting response over current criteria. Addition of endothelial function assessment to current selection criteria may improve the ability to identify CRT responders.
authors.affiliation: Department of Medicine, Division of Cardiology, Loyola University Medical Center, Maywood, Illinois 60153, USA. jakar@lumc.edu
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Akar
authors.forename: M Obadah
authors.initials: MO
authors.lastname: Al-Chekakie
authors.forename: Tyler
authors.initials: T
authors.lastname: Fugate
authors.forename: Lynn
authors.initials: L
authors.lastname: Moran
authors.forename: Borislav
authors.initials: B
authors.lastname: Froloshki
authors.forename: Niraj
authors.initials: N
authors.lastname: Varma
authors.forename: Peter
authors.initials: P
authors.lastname: Santucci
authors.forename: David J
authors.initials: DJ
authors.lastname: Wilber
authors.forename: Martin E
authors.initials: ME
authors.lastname: Matsumura
mesh_terms: D000368:Aged; D002304:Cardiac Pacing, Artificial; D004730:Endothelium, Vascular / Q000503:physiopathology*; D005260:Female; D006333:Heart Failure / Q000503:physiopathology* / Q000628:therapy*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D011788:Quality of Life; D013318:Stroke Volume; D011795:Surveys and Questionnaires; D016896:Treatment Outcome; D016277:Ventricular Function, Left