[Nathans_Dad]

It is true that most acute MIs are caused not by anginal type lesions that slowly block off an artery, but by smaller plagues which have a thinner fibrous wall and thus rupture more easily. Once they rupture, all the cholesterol inside is exposed to the bloodstream which causes a clot. The clot is actually what blocks off the artery, hence the use of "clot busting" drugs to open arteries back up during a heart attack.

The ones we fix with angioplasty and stents are usually the ones that cause anginal chest pain, that is chest pain with a certain level of exertion. That's more of a supply/demand issue with exercise. Sometimes those rupture too, but not as often as the smaller ones.

During my residency the chair of the program (a well known cardiologist) was working on using an ultrasound probe you could pass into the artery to see how thick the wall of a given plaque was. Then you could pick out the thin walled ones and do prophylactic treatment on them. Never heard what came of it...maybe he is still working on it.