title: Circadian variation of late potentials in idiopathic ventricular fibrillation associated with J waves: insights into alternative pathophysiology and risk stratification.
abstract: BACKGROUND
  The presence of J waves on ECGs is related to idiopathic ventricular fibrillation (VF).
  
  
  OBJECTIVE
  The purpose of this study was to investigate the pathophysiology of J waves by assessing risk markers that reflect electrophysiologic abnormalities.
  
  
  METHODS
  The study enrolled 22 idiopathic VF patients (17 men and 5 women; mean age 36 +/- 13 years). Patients were divided into two groups according to the presence or absence of J waves. The following risk stratifiers were assessed: late potentials (LPs; depolarization abnormality marker) for 24 hours using a newly developed signal-averaging system, and T-wave alternans and QT dispersion (repolarization abnormality markers). Frequency-domain heart rate variability (HRV), which reflects autonomic modulation, also was assessed. The results were compared to those of 30 control subjects with J waves and 30 with no J wave, matched for age and gender to the idiopathic VF patients.
  
  
  RESULTS
  J waves were present in 7 (32%) idiopathic VF patients. The incidence of LP in the idiopathic VF J-wave group was higher than in the idiopathic VF non-J-wave group (86% vs 27%, P = .02). In contrast, repolarization abnormality markers did not differ between the two groups. In the idiopathic VF J-wave group, dynamic changes in LP parameters (fQRS, RMS(40), LAS(40)) were observed and were pronounced at nighttime; this was not the case in the idiopathic VF non-J-wave group and the control J-wave group. High-frequency components (vagal tone index) on frequency-domain HRV analysis were associated with J waves in idiopathic VF patients (P < .05).
  
  
  CONCLUSIONS
  Idiopathic VF patients with J waves had a high incidence of LP showing circadian variation with night ascendancy. J waves may be more closely associated with depolarization abnormality and autonomic modulation than with repolarization abnormality.
authors.affiliation: Second Department of Internal Medicine, Kyorin University School of Medicine, Tokyo, Japan.
authors.forename: Atsuko
authors.initials: A
authors.lastname: Abe
authors.forename: Takanori
authors.initials: T
authors.lastname: Ikeda
authors.forename: Takehiro
authors.initials: T
authors.lastname: Tsukada
authors.forename: Haruhisa
authors.initials: H
authors.lastname: Ishiguro
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Miwa
authors.forename: Mutsumi
authors.initials: M
authors.lastname: Miyakoshi
authors.forename: Hisaaki
authors.initials: H
authors.lastname: Mera
authors.forename: Satoru
authors.initials: S
authors.lastname: Yusu
authors.forename: Hideaki
authors.initials: H
authors.lastname: Yoshino
mesh_terms: D000200:Action Potentials; D000328:Adult; D001341:Autonomic Nervous System; D015415:Biomarkers; D018780:Body Surface Potential Mapping; D016022:Case-Control Studies; D002940:Circadian Rhythm; D015716:Electrocardiography, Ambulatory; D005260:Female; D006329:Heart Conduction System; D006339:Heart Rate; D006352:Heart Ventricles / Q000294:innervation / Q000473:pathology; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D018570:Risk Assessment; D012307:Risk Factors; D012815:Signal Processing, Computer-Assisted; D013997:Time Factors; D014693:Ventricular Fibrillation / Q000453:epidemiology / Q000209:etiology / Q000473:pathology*
chemical_list: D015415:Biomarkers