Original Research ARTICLE
Higher dispersion measures of conduction and repolarization in type 1 compared to non-type 1 Brugada syndrome patients: an electrocardiographic study from a single centre
- 1Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong
- 2Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong
- 3JC School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong
- 4Newcastle University, United Kingdom
- 5Second Hospital of Tianjin Medical University, China
- 6Evaggelismos General Hospital, Greece
- 7School of Life Sciences, The Chinese University of Hong Kong, Hong Kong
- 8Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Hong Kong
Background: Brugada syndrome (BrS) is a cardiac ion channelopathy that predisposes affected individuals to sudden cardiac death. Type 1 BrS is thought to take a more malignant clinical course than non-type 1 BrS. We hypothesized that the degrees of abnormal repolarization and conduction are greater in type 1 subjects and these differences can be detected by electrocardiography (ECG).
Methods: Electrocardiographic data from spontaneous type 1 and non-type 1 BrS patients were analyzed. ECG parameters were measured from leads V1 to V3. Values were expressed as median [lower quartile-upper quartile] and compared using Kruskal-Wallis ANOVA.
Results: Compared to non-type 1 BrS patients (n=29), patients with spontaneous type 1 patterns (n=22) showed similar (P>0.05) heart rate (73 [64-77] vs. 68 [62-80] bpm), QRS duration (136 [124-161] vs. 127 [117-144] ms), uncorrected QT (418 [393-443] vs. 402 [386-424] ms) and corrected QT intervals (457 [414-474] vs. 430 [417-457] ms), JTpeak intervals (174 [144-183] vs. 174 [150-188] ms), Tpeak - Tend intervals (101 [93-120] vs. 99 [90-105] ms), Tpeak - Tend/QT ratios (0.25 [0.23-0.27] vs. 0.24 [0.22-0.27]), Tpeak - Tend/QRS (0.77 [0.62-0.87] vs. 0.77 [0.69-0.86]), Tpeak - Tend/(QRS x QT) (0.00074 [0.00034-0.00096] vs. 0.00073 [0.00048-0.00012] ms-1), index of Cardiac Electrophysiological Balance (iCEB, QT/QRS, marker of wavelength: 3.14 [2.56-3.35] vs. 3.21 [2.85-3.46]) and corrected iCEB (QTc/QRS: 3.25 [2.91-3.73] vs. 3.49 [2.99-3.78]). Higher QRS dispersion was seen in type 1 subjects (QRSd: 34 [24-66] vs. 24 [12-34] ms) but QT dispersion (QTd: 48 [39-71] vs. 43 [22-94] ms), QTc dispersion (QTcd: 52 [41-79] vs. 46 [23-104] ms), JTpeak dispersion (44 [23-62] vs. 45 [30-62] ms), Tpeak - Tend dispersion (28 [15-34] vs. 29 [22-53] ms) or Tpeak - Tend/QT dispersion (0.06 [0.03-0.08] vs. 0.08 [0.04-0.12]) did not differ between the two groups. Type 1 subjects showed higher (QRSd x Tpeak - Tend)/QRS (25 [19-44] vs. 19 [9-30] ms) but similar iCEB dispersion (0.83 [0.49-1.14] vs. 0.61 [0.34-0.92]) and iCEBc dispersion (0.93 [0.51-1.15] vs. 0.65 [0.39-0.96]).
Conclusion: Higher levels of dispersion in conduction and repolarization are found in type 1 than non-type 1 BrS patients, potentially explaining the higher incidence of ventricular arrhythmias in the former group.
Keywords: Electrocardiography, conduction, wavelength, Repolarization, Brugada Syndrome
Received: 16 May 2018;
Accepted: 04 Sep 2018.
Edited by:Pedro Brugada, Independent researcher
Reviewed by:Moisés Rodríguez-Mañero, Universidade de Santiago de Compostela, Spain
Antonio Sorgente, Cleveland Clinic Abu Dhabi, United Arab Emirates
Copyright: © 2018 Tse, Li, Li, Liu, Wong, Bazoukis, Wong, Chan, Wong, Letsas, Chan, Chan and Wu. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Dr. Gary Tse, The Chinese University of Hong Kong, Department of Medicine and Therapeutics, Shatin, Hong Kong, email@example.com