title: Intracardiac J-point elevation before the onset of polymorphic ventricular tachycardia and ventricular fibrillation in patients with an implantable cardioverter-defibrillator.
abstract: BACKGROUND
  The clinical importance of the J-point elevation on electrocardiogram is controversial.
  
  
  OBJECTIVE
  To study intracardiac J-point amplitude before ventricular arrhythmia.
  
  
  METHODS
  Baseline 12-lead electrocardiogram and far-field right ventricular intracardiac implantable cardioverter-defibrillator electrograms were recorded at rest in 494 patients (mean age 60.4 ± 13.1 years; 360 [72.9%] men) with structural heart disease (278 [56.3%] ischemic cardiomyopathy) who received primary (463 [93.9%] patients) or secondary prevention implantable cardioverter-defibrillator. Ten-second intracardiac far-field electrograms before the onset of arrhythmia were compared with the baseline. The J-point amplitude was measured on the baseline 12-lead surface electrocardiogram and the intracardiac far-field electrogram. The relative J-point amplitude was calculated as the ratio of J-point amplitude to peak-to-peak R-wave.
  
  
  RESULTS
  The paired t test showed that the relative intracardiac J-point amplitude was significantly higher before polymorphic ventricular tachycardia/ventricular fibrillation (VF) onset (0.28 ± 0.08 vs -0.19 ± 0.39; P = .012) than at baseline. In a mixed-effects logistic regression model, adjusted for multiple episodes per patient, each 10% increase in relative J-point amplitude increased the odds of having ventricular tachycardia/VF by 13% (odds ratio 1.13 [95% confidence interval 1.07-1.19]; P < .0001) and increased the odds of having polymorphic ventricular tachycardia/VF by 27% (odds ratio 1.27 [95% confidence interval 1.11-1.46]; P = .001).
  
  
  CONCLUSIONS
  The relative intracardiac J-point amplitude is augmented immediately before the onset of polymorphic ventricular tachycardia/VF in patients with structural heart disease.
authors: Division of Cardiology, Department of Medicine, Johns Hopkins Hospital, 600 N Wolfe St., Baltimore, MD 21287, USA. lteresh1@jhmi.edu
authors: Larisa G
authors: LG
authors: Tereshchenko
authors: Aaron
authors: A
authors: McCabe
authors: Lichy
authors: L
authors: Han
authors: Sanjoli
authors: S
authors: Sur
authors: Timothy
authors: T
authors: Huang
authors: Joseph E
authors: JE
authors: Marine
authors: Alan
authors: A
authors: Cheng
authors: David D
authors: DD
authors: Spragg
authors: Sunil
authors: S
authors: Sinha
authors: Hugh
authors: H
authors: Calkins
authors: Kenneth
authors: K
authors: Stein
authors: Gordon F
authors: GF
authors: Tomaselli
authors: Ronald D
authors: RD
authors: Berger
mesh_terms: D016009:Chi-Square Distribution; D017147:Defibrillators, Implantable; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D017180:Tachycardia, Ventricular / Q000503:physiopathology*; D014693:Ventricular Fibrillation / Q000503:physiopathology*