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0210 : Effect of SCN5A mutations and SCN10A, SCN5A and HEY2 frequent variants on ECG of Brugada patients during ajmaline test

Abstract : Introduction Inactivating mutations in the SCN5A and frequent variants in SCN10A, SCN5A and HEY2 genes have been both associated with Brugada syndrome. The myocardial transmural electrical gradient that could explain the ‘Brugada’ ECG pattern, is considered as increased by inactivation of the sodium channel. Na channel blocker drug can likewise increase or unmask this pattern. To better assess phenotype correlation with those SCN5A mutation and frequent variants, we compare ECG parameters during Na channel blocker test according to the genetical status. Methods ECG parameters (P, PR, QRS, QT peak and QT end intervals; J wave amplitude in V1, V2, V3) were double measured in 73 unrelated Brugada patients with a positive Na blocker challenge. Data were measured at baseline and at the end of the test. Each patient was screened for SCN5A mutation and SCN10A, SCN5A and HEY2 frequent variants by direct sequencing and genotyped using Axiom Genome-Wide CEU 1 arrays (Affymetrix). Results The 10 patients carrying known SCN5A mutations (14%) didn’t show any clinical differences at baseline with those without SCN5A mutation. Baseline ECGs revealed a lengthening of PR (181 ±27 vs 156 ±30 p=0.017) and QRS interval (101 ±15 vs 89 ±14 p=0.020). No other parameter was significantly different. Once ECG parameters fulfilled diagnostic criteria for Brugada pattern, ECG parameters were not significantly different in the 2 groups. A similar effect on ECG was found in patients without SCN5A mutations but carrying more than 4 frequent variants. SCN10A polymorphism (rs10428132) was associated with a progressive effect on PR (p=0.044) and QRS (p=0.030) duration according to the risk allele number. According to the genetic status, no clinical difference was found after a mean follow up of 6 years. Conclusion Frequent variants associated with Brugada syndrome could present the same effect on ECG than SCN5A mutations. Lengthening of PR and QRS interval observed at baseline in those patients disappears during NA blocker test suggesting a non cumulative and a saturable effect of SCN5A in brugada syndrome’s pathophysiology.
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https://hal-univ-rennes1.archives-ouvertes.fr/hal-01150488
Contributor : Laurent Jonchère <>
Submitted on : Monday, May 11, 2015 - 1:35:29 PM
Last modification on : Wednesday, June 10, 2020 - 6:42:06 PM

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Dylan Therasse, Floriane Simonet, Christian Dina, Aurélie Thollet, Philippe Mabo, et al.. 0210 : Effect of SCN5A mutations and SCN10A, SCN5A and HEY2 frequent variants on ECG of Brugada patients during ajmaline test. Archives of Cardiovascular Diseases Supplements, Apr 2015, Toulouse, France. pp.170--171, ⟨10.1016/S1878-6480(15)30108-7⟩. ⟨hal-01150488⟩

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