Myosin modulator Aficamten inhibits force in cardiac muscle by altering myosin’s biochemical activity without changing thick filament structure

We used a combination of biochemical and biomechanical assays to show that Aficamten inhibits myosin ATPase without appreciably altering myosin structure. This is different from Mavacamten that strongly affects both. While both compounds inhibit contractility, differences in mechanisms of action and kinetics of force activation and relaxation could allow use in different patient populations.