Key Points
- To identify the biophysical mechanisms and channel gating properties that regulate flecainide use-dependent block across SCN5A mutations linked to Brugada syndrome and Long QT syndrome variant 3.
- Examined use-dependent block by flecainide across a panel of disease-linked SCN5A alpha-subunit mutations causing Brugada syndrome or Long QT syndrome variant 3.
- Analyzed the relationship between voltage-dependent activation, channel availability (inactivation), and drug-channel interactions during repetitive depolarization.
- Demonstrated that flecainide use-dependent block requires prior channel opening but does not occur primarily via open-state channel block.
- Identified that flecainide preferentially interacts with inactivation states following depolarization, such that mutation-driven changes in inactivation voltage dependence directly alter drug sensitivity regardless of clinical syndrome type.
Structured PICO
PPopulationCardiac voltage-gated Na+ channels with SCN5A mutations linked to Brugada syndrome (BrS) and LQT-3
OOutcomeMechanism of use-dependent block (UDB) and interaction with channel inactivation statessurrogate
Flecainide interacts with inactivation states following channel opening, providing molecular insights into its action on mutant SCN5A channels in Brugada and LQT-3 syndromes.