title: RMSSD, a measure of vagus-mediated heart rate variability, is associated with risk factors for SUDEP: the SUDEP-7 Inventory.
abstract: OBJECTIVE
  The goal of this study was to determine if specific measures of heart rate variability (HRV) are associated with the total score on a new seven-item inventory for sudden unexplained death in epilepsy (SUDEP).
  
  
  METHODS
  Nineteen subjects with intractable partial seizures, at least three per month, were enrolled in a randomized clinical trial of omega-3 fatty acids in epilepsy. At study entry, subjects underwent a 1-hour ECG recording for the determination of HRV. To estimate the risk of SUDEP, we assembled a seven-item inventory (the SUDEP-7 Inventory) from risk factors prospectively validated by T.S. Walczak, I.E. Leppik, M. D'Amelio M, et al. (Neurology 2001;56:519-25). The SUDEP-7 score was then correlated with measures of HRV using the Pearson correlation and other parametric and nonparametric methods.
  
  
  RESULTS
  Subjects had highly drug-resistant seizures, with a mean seizure frequency of 22.8 seizures per month. Scores on the SUDEP-7 inventory ranged from 1 to 7 of a maximum possible score of 12. RMSSD, a measure of high-frequency HRV, was inversely correlated with the SUDEP-7 score, r=-0.64, P=0.004. Subjects with higher SUDEP-7 scores had reduced levels of HRV (RMSSD). Other time-dependent measures of HRV (SDNN, SDANN) were not significantly correlated with SUDEP risk scores.
  
  
  CONCLUSIONS
  RMSSD, a measure of HRV, which reflects the integrity of vagus nerve-mediated autonomic control of the heart, is highly associated with the total score on a new seven-item SUDEP risk inventory. Lower RMSSD values were associated with higher risk scores on the new SUDEP risk inventory. This provides new evidence that HRV (specifically RMSSD) is a marker of SUDEP risk.
authors.affiliation: Department of Neurology, David Geffen-UCLA School of Medicine, Los Angeles, CA 90095, USA. cmd@mednet.ucla.edu
authors.forename: Christopher M
authors.initials: CM
authors.lastname: DeGiorgio
authors.forename: Patrick
authors.initials: P
authors.lastname: Miller
authors.forename: Sheba
authors.initials: S
authors.lastname: Meymandi
authors.forename: Alex
authors.initials: A
authors.lastname: Chin
authors.forename: Jordan
authors.initials: J
authors.lastname: Epps
authors.forename: Steven
authors.initials: S
authors.lastname: Gordon
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Gornbein
authors.forename: Ronald M
authors.initials: RM
authors.lastname: Harper
mesh_terms: D000328:Adult; D003645:Death, Sudden; D004311:Double-Blind Method; D004562:Electrocardiography / Q000379:methods; D004828:Epilepsies, Partial / Q000178:diet therapy / Q000503:physiopathology*; D015525:Fatty Acids, Omega-3 / Q000627:therapeutic use; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018570:Risk Assessment; D012307:Risk Factors; D014630:Vagus Nerve / Q000502:physiology*; D055815:Young Adult
chemical_list: D015525:Fatty Acids, Omega-3