title: High-frequency powers hidden within QRS complex as an additional predictor of lethal ventricular arrhythmias to ventricular late potential in post-myocardial infarction patients.
abstract: BACKGROUND
  Ventricular late potentials (VLPs) have been known to be a predictor of lethal ventricular arrhythmias (L-VAs); however, detection of other arrhythmogenic signals within the QRS complex remains obscure.
  
  
  OBJECTIVE
  The aim of this study was to evaluate whether abnormal intra-QRS high-frequency powers (IQHFP) within the QRS complex become a new predictor of L-VAs in addition to VLPs.
  
  
  METHODS
  Both 12-lead electrocardiograms (ECG) and VLPs were recorded from 142 subjects, including 37 patients without heart diseases, 97 patients post-myocardial infarction (MI), and 45 post-MI patients with L-VAs. Time-frequency analysis of ECG (leads V(1) or II) using wavelet transform with the Morlet function was performed. After the time-frequency powers were calculated, the ratios of the peak of signal power during the QRS complex in high-frequency bands against the peak power at 80 Hz (b/a ratio; P100, P150, P200, P250, or P300Hz/P80Hz) were measured. Abnormal IQHFP was defined when the b/a ratio exceeded the optimal cut-off values estimated by receiver-operator characteristic curves.
  
  
  RESULTS
  The combination of abnormal IQHFP appearing at 200, 250, and 300 Hz with positive VLPs increased the sensitivity for prediction of L-VAs from 53.3% by VLPs to 89.5%, and the negative predictive value from 74.7% by VLPs to 87.7%.
  
  
  CONCLUSIONS
  The combined use of VLPs and IQHFP hidden within the QRS complex improved the prediction of L-VAs in post-MI patients.
authors: Division of Cardiology, Eda Memorial Hospital, Yokohama, Japan. ttsutsumi07@gmail.com
authors: Takeshi
authors: T
authors: Tsutsumi
authors: Nami
authors: N
authors: Takano
authors: Narihisa
authors: N
authors: Matsuyama
authors: Yukei
authors: Y
authors: Higashi
authors: Kuniaki
authors: K
authors: Iwasawa
authors: Toshiaki
authors: T
authors: Nakajima
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D000789:Angina, Unstable / Q000175:diagnosis / Q000503:physiopathology*; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006352:Heart Ventricles / Q000503:physiopathology*; D006801:Humans; D008297:Male; D009203:Myocardial Infarction / Q000175:diagnosis / Q000503:physiopathology*; D011237:Predictive Value of Tests; D012372:ROC Curve; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000503:physiopathology*; D014693:Ventricular Fibrillation / Q000175:diagnosis / Q000503:physiopathology*