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Double SCN5A mutation underlying asymptomatic Brugada syndrome
Hisataka Yokoi1, Naomasa Makita, Koji Sasaki
1Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
Heart Rhythm
|April 27, 2005
Summary
Asymptomatic Brugada syndrome patients generally have a good prognosis, but some may face a poor outlook. Genetic mutations can cause subclinical channel dysfunction, indicating unknown factors influence arrhythmia risk.
Area of Science:
- Cardiology
- Genetics
- Electrophysiology
Background:
- Brugada syndrome patients with syncope or aborted sudden death face high risks of lethal arrhythmias.
- Prognosis and treatment for asymptomatic individuals with Brugada-type ECG remain controversial.
Observation:
- Thirty asymptomatic Brugada syndrome probands underwent genetic screening.
- Most patients remained symptom-free for at least three years; one with a family history of sudden death died.
- Programmed electrical stimulation induced ventricular fibrillation in 78% of subjects, but no spontaneous arrhythmias occurred.
Findings:
- SCN5A mutations were identified in some cases, including a novel double missense mutation.
- This mutation caused altered sodium channel function, suggesting subclinical channel dysfunction.
- Asymptomatic individuals with Brugada-type ECG generally have a better prognosis than symptomatic patients.
Implications:
- A subset of asymptomatic Brugada syndrome patients may have a poor prognosis.
- Severe sodium channel dysfunction alone may not cause symptoms or arrhythmias.
- Unknown factors or modifier genes likely influence arrhythmogenesis in Brugada syndrome.