Stages of Coronary Artery Disease

In a normal heart, the coronary arteries are clear. Clear arteries provide the heart with adequate oxygen. When the arteries are narrowed or partially blocked, angina results. When the coronary artery is fully blocked, a heart attack can occur.

Diagram showing coronary artery disease

When the coronary artery is clear, blood can flow freely providing the heart with oxygen as needed.

Normal artery showing clear passage for blood to flow

When the coronary artery is partially blocked, limited amount of blood can flow to supply the heart with oxygen. This lead to a heart condition called angina. Angina can be mild or severe. When enough clots are formed, a severe case of angina called unstable angina occurs.

Partially blocked coronary artery leading to a heart condition called angina.

When the coronary artery is fully blocked, blood cannot flow into the heart to supply the heart with any oxygen. This results in a heart attack.

Blocked artery leads to a heart attack.