title: Characteristics of responders to cardiac resynchronization therapy: the impact of echocardiographic left ventricular volume.
abstract: BACKGROUND
  One-third of patients who receive cardiac resynchronization therapy (CRT) are classified as nonresponders. Characteristics of responders to CRT have been studied in multiple clinical trials.
  
  
  OBJECTIVE
  Independent predictors of CRT response may be identified by studying a series of patients in routine clinical practice.
  
  
  METHODS
  One hundred twenty-five patients were examined retrospectively from a multidisciplinary CRT clinic program. Echocardiographic CRT response was defined as a decrease in left ventricular (LV) end-systolic volume of ≥15% and/or absolute increase of 5% in LV ejection fraction at the 6-month visit.
  
  
  RESULTS
  There were 81 responders and 44 nonresponders. By univariate analyses, female sex, nonischemic cardiomyopathy etiology, baseline QRS duration, the presence of left bundle branch block (LBBB), and left ventricular end-diastolic volume (LVEDV) index predicted CRT response. However, multivariate analysis demonstrated that only QRS duration, LBBB, and LVEDV index were independent predictors (QRS width, odds ratio [OR]: 1.027, 95% confidence interval [CI]: 1.004-1.050, P = 0.023; LBBB, OR: 3.568, 95% CI: 1.284-9.910, P = 0.015; LVEDV index, OR: 0.970, 95% CI: 0.953-0.987, P = 0.001). Although female sex and nonischemic etiology were associated with an improved CRT response on univariate analyses, after adjusting for LV volumes they were not independent predictors.
  
  
  CONCLUSIONS
  QRS width, LBBB, and LVEDV index are independent predictors for echocardiographic CRT response. Previously reported differences in CRT response for sex and cardiomyopathy etiology are associated with differences in baseline LV volumes in our clinical practice.
authors.affiliation: Heart Center, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA.
authors.forename: Mi Young
authors.initials: MY
authors.lastname: Park
authors.forename: Robert K
authors.initials: RK
authors.lastname: Altman
authors.forename: Mary
authors.initials: M
authors.lastname: Orencole
authors.forename: Prabhat
authors.initials: P
authors.lastname: Kumar
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Parks
authors.forename: Kevin E
authors.initials: KE
authors.lastname: Heist
authors.forename: Jagmeet P
authors.initials: JP
authors.lastname: Singh
authors.forename: Michael H
authors.initials: MH
authors.lastname: Picard
mesh_terms: D000368:Aged; D058406:Cardiac Resynchronization Therapy; D004452:Echocardiography; D004562:Electrocardiography; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D013318:Stroke Volume