SCN5A mutation associated with acute myocardial infarction

Area of Science:

• Cardiovascular Genetics
• Molecular Cardiology
• Cardiac Electrophysiology

Background:

• Ventricular tachycardia/fibrillation (VT/VF) in Brugada syndrome and acute myocardial infarction (AMI) share mechanistic similarities, potentially involving phase 2 reentry.
• The SCN5A gene encodes a crucial sodium channel subunit implicated in cardiac electrical activity.

Purpose of the Study:

• To investigate the contribution of SCN5A gene mutations to the development of VT/VF during AMI.
• To identify genetic factors predisposing to severe arrhythmias in the context of acute ischemia.

Main Methods:

• Whole-cell patch-clamp electrophysiology was used to study wild-type and mutant SCN5A genes co-expressed with SCN1B in TSA201 cells.
• Genetic analysis was performed on 19 consecutive patients experiencing VF during AMI.

Main Results:

• A novel missense mutation (G400A) in the SCN5A gene was identified in one patient.
• This mutation, along with an H558R polymorphism on the same allele, was associated with an arrhythmic storm (six VT/VF episodes) during AMI.
• The mutation carrier experienced significantly more VT/VF episodes compared to other patients.

Conclusions:

• This study identifies the first sodium channel mutation linked to arrhythmic storm during acute ischemia.
• Loss of function in SCN5A may increase susceptibility to ischemia-induced VT/VF.
• Findings have implications for genetic screening in relatives and forensic investigations.