The acute phase of coronary disease can develop in a matter of seconds.
It involves spontaneous rupture of a cholesterol blockage (plaque) and the development of thrombus (blood clot) which compromises blood flow and can quickly result in heart damage.
Frequently it can first manifest itself as sudden death.
When a vulnerable atherosclerotic plaque ruptures, material is released into the bloodstream and causes the blood to clot.
The degree of clot can restrict blood flow ranging from mildly limiting to complete total occlusion.
The severity of the acute coronary syndrome depends on how much flow is restricted.
In an Acute Coronary Syndrome, the alteration in blood flow to the heart can cause a characteristic change in the EKG, more specifically, in the ST segment.
If blood flow is cut off completely, as it is in a full -blow heart attack, the ST segments will elevate. As a result this kind of heart attack has been named a STEMI or ST elevation Myocardial Infarction.
If the interruption of blood flow is partial, i.e. a mini-heart attack or unstable angina, then the ST segments become depressed or you can see inversion of the T wave portion. This type of acute coronary syndrome is called a non-STEMI or non- ST elevation Myocardial Infarction.