The SCN5A R558 allele, present in one-third of the population, thus constitutes a risk factor for lone AF and may increase susceptibility to sodium channel blocker-induced proarrhythmia.
The purpose of this study was to describe the first family associating LQT-3 and AF due to a gain-of-function mutation in SCN5A and assess the usefulness of the sodium blocker flecainide in individuals with both phenotypes.
In view of the pleiotropic effects of SCN5A mutations, the purpose of this study was to examine a cohort of patients with familial atrial fibrillation (AF) for mutations in the SCN5A gene.
We describe the development of a Brugada ECG together with sinus- and ventricular arrest after intravenous flecainide for atrial fibrillation in a patient in whom eventually a SCN5a mutation was identified.
Furthermore, several of the arrhythmogenic diseases, such as long-QT syndrome, Brugada syndrome, and AF, reported to be associated with mutations in SCN5A, are thoroughly described.
Mutations in the SCN5A gene have been linked to Brugada syndrome (BrS), conduction disease, Long QT syndrome (LQT3), atrial fibrillation (AF), and to pre- and neonatal ventricular arrhythmias.
Screening of SCN5A-the gene encoding the α-subunit of the cardiac sodium channel-has indicated that disturbances of the sodium current may play a central role in the mechanism of lone AF.
Of 15 SCN5A mutation carriers in our study, 14 (93%) manifested arrhythmia: supraventricular arrhythmia (13 of 15), including sick sinus syndrome (5 of 15) and atrial fibrillation (9 of 15), ventricular tachycardia (5 of 15), and conduction disease (9 of 15).