Pathogenesis
The disease process underlying most ischaemic heart disease is atherosclerosis of the coronary arteries. The arteries become "furred up" by fat-rich deposits in the vessel wall (plaques).
Stable angina is due to inability to supply the myocardium (heart muscle) with sufficient blood in situations of increased cardiac output (such as exertion), and this pain of stable angina normally resolves with rest or nitroglicerin (sublingual spray or tablet).
Unstable angina, STEMI and NSTEMI are attributed to "plaque rupture", where one of the plaques gets weakened, develops a tear, and forms an adherent blood clot that either obstructs blood flow or floats further down the blood vessel, causing obstruction there.
Read more about this topic: Ischaemic Heart Disease