title: Electrical Dyssynchrony on Noninvasive Electrocardiographic Mapping correlates with SAI QRST on surface ECG.
abstract: OBJECTIVE
  The goal of this study was to compare associations between clinical and ECG predictors of cardiac resynchronization therapy (CRT) response with electrical dyssynchrony.
  
  
  METHODS
  Body-surface potentials were recorded using a 120-lead system in 4 patients (age 62 ± 12 y, left ventricular ejection fraction (LVEF) 29 ± 5 %; QRS duration 154 ± 19 ms) with post-myocardial infarction scar and left bundle branch block before CRT implantation. A patient-specific heart-torso model derived from MRI with 291 heart-surface nodes was developed. Electrical dyssynchrony index (EDI) was computed as the standard deviation of activation times on the epicardium while uncoupling index (UI) was measured as the difference between the activation times.
  
  
  RESULTS
  QRS duration correlated with mean activation time (r = 0.977; P = 0.023), but did not correlate with EDI or UI. LVEF inversely correlated with activation time at the lowest 20thpercentile (r = -0.960; P = 0.040). Sum absolute QRST integral (SAI QRST), measured on orthogonal XYZ ECG, correlated with EDI (r = 0.955; P = 0.045), and characterized late-activated area of the left ventricle.
  
  
  CONCLUSIONS
  SAI QRST is a measure of electrical dyssynchrony on ECG.
authors.affiliation: Oregon Health and Science University, Knight Cardiovascular Institute, Portland, OR, USA; Johns Hopkins University School of Medicine, Cardiovascular Division, Baltimore, MD, USA.
authors.forename: Larisa G
authors.initials: LG
authors.lastname: Tereshchenko
authors.affiliation: Oregon Health and Science University, Knight Cardiovascular Institute, Portland, OR, USA.
authors.forename: Elyar
authors.initials: E
authors.lastname: Ghafoori
authors.affiliation: Oregon Health and Science University, Knight Cardiovascular Institute, Portland, OR, USA.
authors.forename: Muammar M
authors.initials: MM
authors.lastname: Kabir
authors.affiliation: Johns Hopkins University School of Medicine, Cardiovascular Division, Baltimore, MD, USA.
authors.forename: Markus
authors.initials: M
authors.lastname: Kowalsky