[1] The endocardium underlies the much more voluminous myocardium, the muscular tissue responsible for the contraction of the heart.

[2] The endocardium, which is primarily made up of endothelial cells, controls myocardial function.

This modulating role is separate from the homeometric and heterometric regulatory mechanisms that control myocardial contractility.

Additionally, the contractility and electrophysiological environment of the cardiomyocyte are regulated by the cardiac endothelium.

[9] In the chronic setting, transmural infarctions are more dangerous due to the greater amount of muscular damage and the development of scar tissue leading to impaired systolic contractility, impaired diastolic relaxation, and increased risk for rupture and thrombus formation.