title: Susceptibility for ventricular tachycardia and the correlation between depolarization and orthogonal components of repolarization.
abstract: OBJECTIVE
  There is a continuing need of methods to identify subgroups of patients at high risk of ventricular arrhythmias, in particular after myocardial infarction (MI).
  
  
  METHODS
  We performed a singular value decomposition of repolarization potentials in individual recordings in 134 healthy males, in 203 males with old MI and without documented sustained ventricular tachycardia (VT) and in 104 MI males with documented VT. We considered the absolute correlation coefficient between the first orthogonal component, constructed by matrix multiplication of the first left and right singular vectors and the QRS integral (RT1) and a similar index for the second component (RT2).
  
  
  RESULTS
  Abnormally high (more than two standard deviations above the mean) value of the RT1 had a 89% specificity for VT in MI patients. Abnormally low RT2 had specificity of 87%. Both indices combined had a 97% specificity. However, sensitivity of the combined indices was only 13%.
  
  
  CONCLUSIONS
  Abnormalities in the correlation of orthogonal components of repolarization with depolarization are highly specific for a small group of patients with old myocardial infarction at high risk of ventricular tachycardia.
authors.affiliation: University Emergency Hospital of Bucharest, Bucharest, Romania. alexandru@corlan.net
authors.forename: Alexandru Dan
authors.initials: AD
authors.lastname: Corlan
authors.forename: Milan
authors.initials: M
authors.lastname: Horacek
authors.forename: Luigi
authors.initials: L
authors.lastname: De Ambroggi
mesh_terms: D016022:Case-Control Studies; D004198:Disease Susceptibility; D004562:Electrocardiography; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D009203:Myocardial Infarction; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D017180:Tachycardia, Ventricular / Q000175:diagnosis* / Q000503:physiopathology