title: Various patterns of intracardiac electrogram T-wave alternans prior to ventricular tachyarrhythmias in implantable cardioverter-defibrillator patients.
abstract: BACKGROUND
  It has been reported that intracardiac electrogram T-wave alternans (IE-TWA) is greater prior to spontaneous ventricular tachyarrhythmia (VTA) than for baseline recordings.
  
  
  OBJECTIVE
  To investigate IE-TWA just prior to VTA episodes and at baseline and compare these with microvolt TWA (M-TWA) measured during exercise.
  
  
  METHODS
  We analyzed right ventricular ring-can electrogram recordings just prior to VTA episodes and compared T-wave pattern and degree of variation to baseline recordings from 3 patients (2 with idiopathic ventricular fibrillation and 1 with hypertrophic cardiomyopathy) who were enrolled in the Japan Intracardiac Electrogram TWA Study of ICD Recipients. In a stable state, we measured the M-TWA of the surface electrocardiogram during treadmill exercise in these 3 patients.
  
  
  RESULTS
  We found 3 patterns of IE-TWA among these 3 patients with implantable cardioverter-defibrillator immediately prior to spontaneous VTAs. Case 1 had AB pattern of IE-TWA, case 2 ABC pattern, and case 3 nonspecific pattern but great T-wave amplitude variations. These IE-TWA amplitudes and the distribution of T-amplitude difference were greater than at baseline. Case 1 had a positive outcome in regard to the M-TWA determination, whereas cases 2 and 3 did not.
  
  
  CONCLUSIONS
  We indicate different patterns of IE-TWA prior to spontaneous VTAs. The phenomena of IE-TWA correspond to outcomes of M-TWA measured during exercise in the surface electrocardiogram.
authors.affiliation: Department of Cardiovascular Medicine, Toho University Medical Center, Tokyo, Japan. ikety3@gmail.com
authors.forename: Takanori
authors.initials: T
authors.lastname: Ikeda
authors.forename: Satoru
authors.initials: S
authors.lastname: Yusu
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Yokoyama
mesh_terms: D000368:Aged; D017147:Defibrillators, Implantable; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D013610:Tachycardia / Q000503:physiopathology*