Functional Epicardial Conduction Disturbances Due to a SCN5A Variant Associated With Brugada Syndrome.
JACC Clin Electrophysiol
; 9(8 Pt 1): 1248-1261, 2023 08.
Article
em En
| MEDLINE
| ID: mdl-37227351
ABSTRACT
BACKGROUND:
Brugada syndrome is a significant cause of sudden cardiac death (SCD), but the underlying mechanisms remain hypothetical.OBJECTIVES:
This study aimed to elucidate this knowledge gap through detailed ex vivo human heart studies.METHODS:
A heart was obtained from a 15-year-old adolescent boy with normal electrocardiogram who experienced SCD. Postmortem genotyping was performed, and clinical examinations were done on first-degree relatives. The right ventricle was optically mapped, followed by high-field magnetic resonance imaging and histology. Connexin-43 and NaV1.5 were localized by immunofluorescence, and RNA and protein expression levels were studied. HEK-293 cell surface biotinylation assays were performed to examine NaV1.5 trafficking.RESULTS:
A Brugada-related SCD diagnosis was established for the donor because of a SCN5A Brugada-related variant (p.D356N) inherited from his mother, together with a concomitant NKX2.5 variant of unknown significance. Optical mapping demonstrated a localized epicardial region of impaired conduction near the outflow tract, in the absence of repolarization alterations and microstructural defects, leading to conduction blocks and figure-of-8 patterns. NaV1.5 and connexin-43 localizations were normal in this region, consistent with the finding that the p.D356N variant does not affect the trafficking, nor the expression of NaV1.5. Trends of decreased NaV1.5, connexin-43, and desmoglein-2 protein levels were noted; however, the RT-qPCR results suggested that the NKX2-5 variant was unlikely to be involved.CONCLUSIONS:
This study demonstrates for the first time that SCD associated with a Brugada-SCN5A variant can be caused by localized functionally, not structurally, impaired conduction.Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Síndrome de Brugada
Tipo de estudo:
Risk_factors_studies
Limite:
Adolescent
/
Humans
/
Male
Idioma:
En
Ano de publicação:
2023
Tipo de documento:
Article