title: Utility of three-dimensional echocardiography in assessing and predicting response to cardiac resynchronization therapy.
abstract: BACKGROUND
  Cardiac resynchronization therapy (CRT) can be a valuable treatment for heart failure. However, there are high nonresponse rates using current CRT inclusion criteria.
  
  
  OBJECTIVE
  To assess the value of three-dimensional echocardiography (3DE) in predicting response to CRT.
  
  
  METHODS
  Functional assessments and 3DE were performed in heart failure patients pre-CRT, 24 h post-CRT and six to 12 months after CRT. The dyssynchrony index (DI) was calculated as the SD of the time to minimum volume in 16 left ventricle segments corrected by heart rate. Response to CRT was defined as functional improvement (alive at late follow-up with improvement by one New York Heart Association class) and a decrease in left ventricular end-systolic volume by 15% or greater at six to 12 months follow-up.
  
  
  RESULTS
  A total of 53 patients were enrolled. Average 3DE acquisition time was less than 5 min. Seventy-two per cent of patients showed functional improvement, while 43% showed functional and echocardiographic evidence of response. Baseline DI and the decrease in DI at 24 h were both correlated with reverse remodelling. Responders had higher baseline DI values compared with nonresponders (mean 16.8 versus 7.1, P<0.001), and showed a greater decrease in DI values at 24 h (mean decrease 7.9 versus 0.7, P<0.001). All responders had baseline DI values of greater than 10 (negative predictive value of 100%). A decrease in the DI value by more than 5 at 24 h in patients with a baseline DI of greater than 10 identified responders with a positive predictive value of 83%.
  
  
  CONCLUSIONS
  3DE may be valuable in predicting response to CRT. A baseline DI cut-off of greater than 10 in our patients excluded reverse remodelling to CRT. In addition, the decrease in DI at 24 h had a high positive predictive value for long-term response to CRT.
authors.affiliation: Division of Cardiology, Schulich Heart Centre, Sunnybrook Health Sciences Centre, Toronto, Ontario. ching.lau@sunnybrook.ca
authors.forename: Ching
authors.initials: C
authors.lastname: Lau
authors.forename: Husam Mohamed
authors.initials: HM
authors.lastname: Abdel-Qadir
authors.forename: Ilan
authors.initials: I
authors.lastname: Lashevsky
authors.forename: Mark
authors.initials: M
authors.lastname: Hansen
authors.forename: Eugene
authors.initials: E
authors.lastname: Crystal
authors.forename: Campbell
authors.initials: C
authors.lastname: Joyner
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D058406:Cardiac Resynchronization Therapy; D019560:Echocardiography, Three-Dimensional; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011182:Postoperative Care; D011237:Predictive Value of Tests; D011300:Preoperative Care; D012189:Retrospective Studies; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D016896:Treatment Outcome