Effects of danicamtiv, a novel cardiac myosin activator, in heart failure with reduced ejection fraction: experimental data and clinical results from a phase 2a trial

Aims Both left ventricular (LV) and left atrial (LA) dysfunction and remodelling contribute to adverse outcomes in heart failure with reduced ejection fraction (HFrEF). Danicamtiv is a novel, cardiac myosin activator that enhances cardiomyocyte contraction. Methods and results We studied the effects of danicamtiv on LV and LA function in non‐clinical studies (ex vivo: skinned muscle fibres and myofibrils; in vivo: dogs with heart failure) and in a randomized, double‐blind, single‐ and multiple‐dose phase 2a trial in patients with stable HFrEF (placebo, n = 10; danicamtiv, n = 30; 50–100 mg twice daily for 7 days). Danicamtiv increased ATPase activity and calcium sensitivity in LV and LA myofibrils/muscle fibres. In dogs with heart failure, danicamtiv improved LV stroke volume (+10.6 mL, P