Cardiac Sarcomere

The cardiac sarcomere is the fundamental unit of contraction in the heart, composed of a highly organized arrangement of thick and thin filaments (StatPearls) [1]. Its primary biological function is to convert chemical energy from ATP hydrolysis into mechanical force, enabling the heart to pump blood throughout the body (UniProt) [2]. This process is tightly regulated by calcium ions, which bind to the troponin complex to initiate the cross-bridge cycle between myosin and actin (PubMed) [3]. Mutations in sarcomeric proteins, such as cardiac myosin heavy chain (MYH7) or myosin-binding protein C (MYBPC3), are primary causes of inherited cardiomyopathies, including hypertrophic and dilated forms (GeneReviews) [4]. Pharmacological targeting of the cardiac sarcomere has emerged as a precision medicine approach for treating heart failure and cardiomyopathies (Nature Reviews Cardiology) [5]. Small molecule modulators can either increase contractility (activators like omecamtiv mecarbil) or decrease it (inhibitors like mavacamten) by directly binding to cardiac myosin and altering its duty cycle (JACC) [6]. These sarcomere modulators aim to correct the underlying mechanical defects of the heart without the adverse effects associated with traditional inotropes that increase intracellular calcium levels (NEJM) [7]. However, precise dosing is critical, as excessive modulation can lead to significant reductions in ejection fraction or increased myocardial oxygen demand (FDA) [8].

Other names

Cardiac contractile apparatusMyofilamentCardiac muscle contractility machineryCardiac sarcomereSarcomeric proteins

Direct modulation of cardiac myosin ATPase activity (activation or inhibition) and calcium sensitization of the troponin-tropomyosin complex.