Toward Safe Inotropic Therapy:

Early Mechanical Circulatory Support for Cardiogenic Shock

Reversal of cardiogenic shock depends on its early recognition and prompt initiation of therapy. Recognition of the clinical and hemodynamic deterioration that precedes cardiogenic shock is a crucial step in its early detection. Treatment of pre-cardiogenic shock is chiefly pharmacologic with intravenous administration of pressor, inotropic, and loop diuretic agents. Failure to reverse the preshock state with pharmacotherapy entails progression to cardiogenic shock and the need for prompt mechanical circulatory support with membrane oxygenation and possibly left ventricular decompression.

The myosin activator omecamtiv mecarbil: a promising new inotropic agent

Heart failure became a leading cause of mortality in the past few decades with a progressively increasing prevalence. Its current therapy is restricted largely to the suppression of the sympathetic activity and the renin-angiotensin system in combination with diuretics. This restrictive strategy is due to the potential long-term adverse effects of inotropic agents despite their effective influence on cardiac function when employed for short durations. Positive inotropes include inhibitors of the Na⁺/K⁺ pump, β-receptor agonists, and phosphodiesterase inhibitors. Theoretically, Ca²⁺ sensitizers may also increase cardiac contractility without resulting in Ca²⁺ overload; nevertheless, their mechanism of action is frequently complicated by other pleiotropic effects. Recently, a new positive inotropic agent, the myosin activator omecamtiv mecarbil, has been developed. Omecamtiv mecarbil binds directly to β-myosin heavy chain and enhances cardiac contractility by increasing the number of the active force-generating cross-bridges, presumably without major off-target effects. This review focuses on recent in vivo and in vitro results obtained with omecamtiv mecarbil, and discusses its mechanism of action at a molecular level. Based on clinical data, omecamtiv mecarbil is a promising new tool in the treatment of systolic heart failure.