If you have a heart attack in which the artery supplying an area of the heart muscle is partly but not fully blocked, your doctor works out your risk of having a serious heart problem in the future.
If that risk is medium or high, your doctor talks to you about whether you should have a procedure called coronary angiography. In coronary angiography, a specialist passes a fine probe through an artery to your heart, then releases a dye that shows up on X-rays. In this way, your doctors know which arteries are blocked, and how much they are blocked. Then they talk to you about whether it is possible to unblock them, and how best to do so.