title: Heart rate variability and repolarization characteristics in symptomatic and asymptomatic Brugada syndrome.
abstract: OBJECTIVE
  Modulation of ST-segment elevation (STE) and tachyarrhythmic events by the autonomic nervous system (ANS) has been reported in patients with Brugada syndrome (BS). This study examined and compared the autonomic characteristics and STE in symptomatic vs. asymptomatic patients with BS.
  
  
  RESULTS
  We studied 40 symptomatic and 78 asymptomatic patients (mean age = 46.1 ± 13.7 years; 88 men) who underwent 24 h, 12-lead electrocardiograms, and exercise and a head-up tilt tests. Heart rate variability was examined and STE was measured at 5 points between 100 and 140 ms after the onset of 1 min averaged QRS complexes, and the type 1 Brugada pattern was automatically identified. 'Type 1 Brugada burden' was the percentage of averaged type 1 complexes. All measurements were made over 24 h, and during day and night times. During daytime, the variation coefficients of standard deviation of normal-to-normal intervals were 39.0 ± 12.3 vs. 34.1 ± 14.5 ms (P< 0.05) and high frequency normalized units were 39.9 ± 16.9 vs. 33.9 ± 16.2% (P< 0.05) in symptomatic vs. asymptomatic patients, respectively. ST-segment elevation was similar in symptomatic and asymptomatic patients at all time points. The type 1 Brugada burden in V2 was 38.7 ± 33.6% in the symptomatic vs. 24.3 ± 35.2% in the asymptomatic sample, a statistically non-significant difference.
  
  
  CONCLUSIONS
  This analysis of ANS did not identify sensitive predictors of arrhythmic events in patients with BS. We observed, however, greater fluctuations in sinus node response to ANS in symptomatic patients. The type 1 Brugada electrocardiographic pattern was not as reliable a predictor of arrhythmic risk as previously reported.
authors.affiliation: Cardiology and Vascular Disease Division, Rennes University Health Centre, 35033 Rennes cedex, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Behar
authors.affiliation: Cardiology division, GH sud Réunion, 97410 Saint Pierre La Réunion, France.
authors.forename: Bertrand
authors.initials: B
authors.lastname: Petit
authors.affiliation: Cardiology division, Nantes University Health Centre, 44093 Nantes cedex, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Probst
authors.affiliation: LIRYC Institute, INSERM 1045, Bordeaux University Hospital, Bordeaux, France.
authors.forename: Frederic
authors.initials: F
authors.lastname: Sacher
authors.affiliation: Inserm 1414 Clinical Investigation Center, Innovative Technology, Rennes F-35000, France.
authors.forename: Gaelle
authors.initials: G
authors.lastname: Kervio
authors.affiliation: Department of Cardiology, Brest University Health Centre, 29609 Brest, France.
authors.forename: Jacques
authors.initials: J
authors.lastname: Mansourati
authors.affiliation: Cardiology division, La Rochelle Health Centre, 17019 La Rochelle, France.
authors.forename: Paul
authors.initials: P
authors.lastname: Bru
authors.affiliation: INSERM, U1099, Rennes 35000, France.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Hernandez
authors.affiliation: Cardiology and Vascular Disease Division, Rennes University Health Centre, 35033 Rennes cedex, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Mabo
mesh_terms: D000200:Action Potentials; D000328:Adult; D058070:Asymptomatic Diseases; D001341:Autonomic Nervous System / Q000503:physiopathology*; D053840:Brugada Syndrome / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology*; D015716:Electrocardiography, Ambulatory; D005260:Female; D006321:Heart / Q000294:innervation*; D006329:Heart Conduction System / Q000503:physiopathology*; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D013997:Time Factors
keywords: Ambulatory electrocardiogram; Autonomic nervous system; Brugada syndrome; Heart rate variability; Risk stratification