title: Vectorcardiographic QRS area as a novel predictor of response to cardiac resynchronization therapy.
abstract: BACKGROUND
  QRS duration and left bundle branch block (LBBB) morphology are used to select patients for cardiac resynchronization therapy (CRT). We investigated whether the area of the QRS complex (QRSAREA) on the 3-dimensional vectorcardiogram (VCG) can improve patient selection.
  
  
  METHODS
  VCG (Frank orthogonal lead system) was recorded prior to CRT device implantation in 81 consecutive patients. VCG parameters, including QRSAREA, were assessed, and compared to QRS duration and morphology. Three LBBB definitions were used, differing in requirement of mid-QRS notching. Responders to CRT (CRT-R) were defined as patients with ≥15% reduction in left ventricular end systolic volume after 6months of CRT.
  
  
  RESULTS
  Fifty-seven patients (70%) were CRT-R. QRSAREA was larger in CRT-R than in CRT non-responders (140±42 vs 100±40 μVs, p<0.001) and predicted CRT response better than QRS duration (AUC 0.78 vs 0.62, p=0.030). With a 98μVs cutoff value, QRSAREA identified CRT-R with an odds ratio (OR) of 10.2 and a 95% confidence interval (CI) of 3.4 to 31.1. This OR was higher than that for QRS duration >156ms (OR=2.5; 95% CI 0.9 to 6.6), conventional LBBB classification (OR=5.5; 95% CI 0.9 to 32.4) or LBBB classification according to American guidelines (OR=4.5; 95% CI 1.6 to 12.6) or Strauss (OR=10.0; 95% CI 3.2 to 31.1).
  
  
  CONCLUSIONS
  QRSAREA is an objective electrophysiological predictor of CRT response that performs at least as good as the most refined definition of LBBB.
  
  
  CONCLUSIONS
  In 81 candidates for cardiac resynchronization therapy (CRT) we measured the area of the QRS complex (QRSAREA) using 3-dimensional vectorcardiography. QRSAREA was larger in echocardiographic responders than in non-responders and predicted CRT response better than QRS duration and than simple LBBB criteria. QRSAREA is a promising electrophysiological predictor of CRT response.
authors.affiliation: Cardiovascular Research Institute Maastricht, Department of Physiology, Maastricht, the Netherlands; Cardiovascular Research Institute Maastricht, Department of Cardiology, Maastricht, the Netherlands.
authors.forename: Caroline J M
authors.initials: CJ
authors.lastname: van Deursen
authors.affiliation: Cardiovascular Research Institute Maastricht, Department of Cardiology, Maastricht, the Netherlands.
authors.forename: Kevin
authors.initials: K
authors.lastname: Vernooy
authors.affiliation: Cardiovascular Research Institute Maastricht, Department of Cardiology, Maastricht, the Netherlands.
authors.forename: Elton
authors.initials: E
authors.lastname: Dudink
authors.affiliation: Sahlgrenska Academy, Department of Molecular and Clinical Medicine/Cardiology, University of Gothenburg, Sweden.
authors.forename: Lennart
authors.initials: L
authors.lastname: Bergfeldt
authors.affiliation: Cardiovascular Research Institute Maastricht, Department of Cardiology, Maastricht, the Netherlands.
authors.forename: Harry J G M
authors.initials: HJ
authors.lastname: Crijns
authors.affiliation: Cardiovascular Research Institute Maastricht, Department of Physiology, Maastricht, the Netherlands. Electronic address: frits.prinzen@maastrichtuniversity.nl.
authors.forename: Frits W
authors.initials: FW
authors.lastname: Prinzen
authors.affiliation: Karolinska Institutet, Department of Cardiology, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Liliane
authors.initials: L
authors.lastname: Wecke
mesh_terms: D000368:Aged; D000465:Algorithms; D002037:Bundle-Branch Block / Q000175:diagnosis* / Q000517:prevention & control*; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D017063:Outcome Assessment, Health Care / Q000379:methods*; D011379:Prognosis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D014672:Vectorcardiography / Q000379:methods*
keywords: Cardiac resynchronization therapy; QRS area; Vectorcardiography