Is Flecainide Dangerous in Long QT-3 Patients?

Mutations of the cardiac sodium channel gene, SCN5A, are present in both long-QT and Brugada syndromes. Flecainide is used as a provocative test to unmask the electrocardiogram (ECG) phenotype of the Brugada syndrome, as well as long-term treatment for long QT-3 syndrome, since it shortens the QT interval. We report a case where oral flecainide induced syncope with a Brugada ECG pattern in a patient with known long QT-3 syndrome.