title: V-shaped trough in autonomic activity is a possible precursor of life-threatening cardiac events.
abstract: BACKGROUND
  No reliable precursor of sudden cardiac death is known.
  
  
  RESULTS
  Holter electrocardiograms of 34 patients experiencing a cardiac event (event group, 20 deaths) were compared with 191 controls (no event group). The event group included 25 patients with ventricular fibrillation or acute myocardial infarction (AMI), and 9 with cardiac arrest due to complete atrioventricular block. The logarithms were calculated of the moving average of 5 successive values for the low-frequency component (LF), the high-frequency component (HF), and the ratio LF/HF of heart rate variability: ln(LF), ln(HF) and ln(LF/HF). A V-shaped trough appeared in the curve of ln(LF/HF) [sV-trough] or ln(HF) [pV-trough] before such an event in 31 patients in the event group. The V-trough was marked by a small variation lasting 2 h, an abrupt descent lasting 30 min, and a sharp ascent for 40 min. An sV-trough was observed in 22 patients before the onset of ventricular fibrillation or AMI. A pV-trough was observed in all 9 patients before the onset of complete atrioventricular block. In the no event group, an sV-trough and a pV-trough were observed in 10 subjects (5%) and 20 subjects (10%), respectively. The positive predictive accuracy of an sV-trough for ventricular fibrillation or AMI and that of a pV-trough for complete atrioventricular block was 88% and 100%, respectively.
  
  
  CONCLUSIONS
  A previously unidentified V-trough of autonomic activity is a potential precursor of lethal events.
authors.affiliation: Department of Basic Science, Nippon Veterinary and Life Science University, Tokyo, Japan. osaka@nms.ac.jp
authors.forename: Motohisa
authors.initials: M
authors.lastname: Osaka
authors.forename: Eiichi
authors.initials: E
authors.lastname: Watanabe
authors.forename: Hiroshige
authors.initials: H
authors.lastname: Murata
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Fuwamoto
authors.forename: Shinji
authors.initials: S
authors.lastname: Nanba
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Sakai
authors.forename: Takao
authors.initials: T
authors.lastname: Katoh
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D054537:Atrioventricular Block / Q000175:diagnosis*; D001341:Autonomic Nervous System / Q000503:physiopathology*; D016022:Case-Control Studies; D003935:Diagnostic Techniques, Cardiovascular; D015716:Electrocardiography, Ambulatory; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis*; D011237:Predictive Value of Tests; D014693:Ventricular Fibrillation / Q000175:diagnosis*; D055815:Young Adult