While reducing endogenous Na current by 50% was used to simulate general loss of CM excitability (Fig. 5a–f), we further explored the therapeutic potential of BacNav in a simulated Brugada syndrome model (T1620M mutation in SCN5A) of transmural conduction through endocardial, midmyocardial, and epicardial CMs (Fig. 5j–o)34,35. Here, SCN5A is linked to Brugada syndrome.