title: Exaggerated Reactivity of Parasympathetic Nerves Is Involved in Ventricular Fibrillation in J-Wave Syndrome.
abstract: BACKGROUND
  Brugada syndrome (BrS) and early repolarization syndrome (ERS) are termed the J-wave syndrome. In most cases of J-wave syndrome, ventricular fibrillation (VF) often occurs around midnight or in the early morning when parasympathetic tone is augmented.
  
  
  OBJECTIVE
  The purpose of this study was to clarify the relationship between VF and autonomic nervous activity in patients with J-wave syndrome.
  
  
  RESULTS
  We enrolled 28 consecutive patients with J-wave syndrome (20 BrS and 8 ERS) in whom implantable cardioverter defibrillators (ICDs) were implanted between January 2002 and December 2014. Eleven patients (39%) experienced ICD shock delivery due to VF recurrence after ICD implantation (recurrent-VF group). We investigated baroreflex sensitivity (BRS) using the phenylephrine method, heart rate variability (HRV) with Holter electrocardiography, plasma levels of norepinephrine, and cardiac123I-metaiodobenzylguanidine (MIBG) scintigraphy to estimate autonomic nervous function. Upon measurement of HRV, plasma levels of norepinephrine, and123I-MIBG testing, there was no significant difference between recurrent-VF and nonrecurrent-VF groups. However, BRS was significantly higher in the recurrent-VF group than in the nonrecurrent-VF group (P = 0.03). Kaplan-Meier curves suggested that high-BRS patients had higher VF recurrence than those with nonhigh-BRS (P = 0.04). Cox proportional hazards regression analyses showed that high BRS was associated independently with VF recurrence (P = 0.002).
  
  
  CONCLUSIONS
  Our results suggest that exaggerated reactivity of parasympathetic nerves, as represented by increased BRS, may underlie VF in patients with J-wave syndrome.
authors.affiliation: Department of Cardiology and Clinical Examination, Faculty of Medicine, Oita University, Oita, Japan.
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Shinohara
authors.affiliation: Department of Cardiology and Clinical Examination, Faculty of Medicine, Oita University, Oita, Japan.
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Kondo
authors.affiliation: Department of Cardiology and Clinical Examination, Faculty of Medicine, Oita University, Oita, Japan.
authors.forename: Toyokazu
authors.initials: T
authors.lastname: Otsubo
authors.affiliation: Department of Cardiology and Clinical Examination, Faculty of Medicine, Oita University, Oita, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Fukui
authors.affiliation: Department of Cardiology and Clinical Examination, Faculty of Medicine, Oita University, Oita, Japan.
authors.forename: Kunio
authors.initials: K
authors.lastname: Yufu
authors.affiliation: Department of Cardiology and Clinical Examination, Faculty of Medicine, Oita University, Oita, Japan.
authors.forename: Mikiko
authors.initials: M
authors.lastname: Nakagawa
authors.affiliation: Department of Cardiology and Clinical Examination, Faculty of Medicine, Oita University, Oita, Japan.
authors.forename: Naohiko
authors.initials: N
authors.lastname: Takahashi
mesh_terms: D019797:3-Iodobenzylguanidine / Q000008:administration & dosage; D000200:Action Potentials; D000328:Adult; D017704:Baroreflex; D053840:Brugada Syndrome / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy; D016009:Chi-Square Distribution; D002940:Circadian Rhythm; D017147:Defibrillators, Implantable; D018572:Disease-Free Survival; D004554:Electric Countershock / Q000295:instrumentation; D015716:Electrocardiography, Ambulatory; D005260:Female; D006339:Heart Rate; D006352:Heart Ventricles / Q000294:innervation*; D006801:Humans; D007457:Iodine Radioisotopes / Q000008:administration & dosage; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010275:Parasympathetic Nervous System / Q000503:physiopathology*; D016016:Proportional Hazards Models; D019275:Radiopharmaceuticals / Q000008:administration & dosage; D012008:Recurrence; D012307:Risk Factors; D013564:Sympathetic Nervous System / Q000503:physiopathology; D013997:Time Factors; D016896:Treatment Outcome; D014693:Ventricular Fibrillation / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy; D055815:Young Adult
chemical_list: D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine
keywords: Brugada syndrome; J-wave syndrome; autonomic nervous system; baroreflex sensitivity; early repolarization syndrome; parasympathetic nerve activity; ventricular fibrillation