AUTHOR=Tse Gary , Li Ka Hou Christien , Li Guangping , Liu Tong , Bazoukis George , Wong Wing Tak , Chan Matthew T. V. , Wong Martin C. S. , Xia Yunlong , Letsas Konstantinos P. , Chan Gary Chin Pang , Chan Yat Sun , Wu William K. K. 

TITLE=Higher Dispersion Measures of Conduction and Repolarization in Type 1 Compared to Non-type 1 Brugada Syndrome Patients: An Electrocardiographic Study From a Single Center

JOURNAL=Frontiers in Cardiovascular Medicine

VOLUME=5

YEAR=2018

URL=https://www.frontiersin.org/journals/cardiovascular-medicine/articles/10.3389/fcvm.2018.00132

DOI=10.3389/fcvm.2018.00132

ISSN=2297-055X

ABSTRACT=<p><bold>Background:</bold> Brugada syndrome (BrS) is a cardiac ion channelopathy that predisposes affected individuals to sudden cardiac death (SCD). 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).</p><p><bold>Methods:</bold> 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.</p><p><bold>Results:</bold> Compared to non-type 1 BrS patients (<italic>n</italic> = 29), patients with spontaneous type 1 patterns (<italic>n</italic> = 22) showed similar (<italic>P</italic> &gt; 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), JT<sub>peak</sub> intervals (174 [144–183] vs. 174 [150–188] ms), T<sub>peak−</sub> T<sub>end</sub> intervals (101 [93–120] vs. 99 [90–105] ms), T<sub>peak−</sub> T<sub>end</sub>/QT ratios (0.25 [0.23–0.27] vs. 0.24 [0.22–0.27]), T<sub>peak−</sub> T<sub>end</sub>/QRS (0.77 [0.62–0.87] vs. 0.77 [0.69–0.86]), T<sub>peak−</sub> T<sub>end</sub>/(QRS × QT) (0.00074 [0.00034–0.00096] vs. 0.00073 [0.00048–0.00012] ms<sup>−1</sup>), 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), JT<sub>peak</sub> dispersion (44 [23–62] vs. 45 [30–62] ms), T<sub>peak−</sub> T<sub>end</sub> dispersion (28 [15–34] vs. 29 [22–53] ms) or T<sub>peak−</sub> T<sub>end</sub>/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 × T<sub>peak−</sub> T<sub>end</sub>)/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]).</p><p><bold>Conclusion:</bold> 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.</p>