Omecamtiv Mecarbil: A Novel Mechanistic and Therapeutic Approach to Chronic Heart Failure Management

Abstract

Heart failure (HF) is a major public health problem in the United States as well as worldwide. Chronic heart failure is a syndrome of reduced cardiac output resulting from impaired ventricular function, impaired filling, or a combination of both. Associated symptoms include dyspnea, fatigue, and decreased exercise tolerance. HF has a marked effect on morbidity and mortality, given limited therapeutic choices. The first line of therapeutic agents indicated in heart failure are beta-blockers. Other drugs and therapeutic modalities employed in HF treatment include angiotensin-receptor blockers (ARBs), sacubitril (neprilysin inhibitor) combination with the ARB, valsartan, small doses of aldosterone receptor antagonists (ARAs) in the setting of angiotensin-converting enzyme (ACE) inhibitors, and beta-blockers. Additionally, the sodium-glucose transporter-2 inhibitor, dapagliflozin in the setting of ACE inhibitors, ARBs, or sacubitril-valsartan plus beta-blocker have been employed. Other therapeutic modalities have included loop diuretics, digoxin, the hydralazine-isosorbide dinitrate combination, ivabradine, the inotropes, dobutamine, milrinone, and dopamine. Decreased cardiac contractility is central to the systolic HF. Therapeutic agents employed to increase cardiac contractility in HF are limited because of their mechanistic-related adverse effect profiles. Omecamtiv mecarbil (OM) is a first of its class cardiac myosin activator that increases the cardiac contractility by specifically binding to the catalytic S1 domain of cardiac myosin, to be employed in heart failure treatment. This agent has demonstrated benefit in reducing heart rate, peripheral vascular resistance, mean left arterial pressure, and left ventricular end-diastolic pressure in the animal models. Additionally, OM is known to improve systolic wall thickening, stroke volume (SV), and cardiac output (CO). OM increases systolic ejection time (SET), cardiac myocyte fractional shortening without significant increase of LV dP/dtmax, myocardial oxygen consumption, and myocyte intracellular calcium. The benefits of OM have been demonstrated through key trials, as (i) The Acute Treatment with Omecamtiv mecarbil to Increase Contractility in Acute Heart Failure (ATOMIC-AHF), and (ii) The Chronic Oral Study of Myosin Activation to Increase Contractility in Heart Failure (COSMIC-HF). The Global Approach to Lowering Adverse Cardiac Outcomes Through Improving Contractility in Heart Failure (GALACTIC-HF) trial is ongoing and can help provide further clinical data. OM provides a novel mechanism and therapeutic approach to managing patients with HF. Preclinical and clinical data suggest that OM capability can improve cardiac function, decrease ventricular wall stress, reverse ventricular remodeling, and promote sympathetic withdrawal.

Keywords: cardiac contractility; heart failure; omecamtiv mecarbil.