Types of Angina
The three types of angina are stable, unstable, and variant (Prinzmetal's).
Stable Angina
Stable angina is the most common type. It occurs when the heart is working harder than usual. Stable angina has a regular pattern. If you know you have stable angina, you can learn to recognize the pattern and predict when the pain will occur.
Physical exertion is the most common trigger of stable angina. Severely narrowed arteries may allow enough blood to reach the heart when the demand for oxygen is low (such as when you're sitting). But with exertion, like walking up a hill or climbing stairs, the heart works harder and needs more oxygen.
The pain usually goes away in a few minutes after you rest or take your angina medicine.
Stable angina isn't a heart attack, but it makes a heart attack more likely in the future.
Unstable Angina
Unstable angina doesn't follow a pattern. It can occur with or without physical exertion and isn't relieved by rest or medicine.
Unstable angina is very dangerous and needs emergency treatment. It's a sign that a heart attack may happen soon.
Blood clots that partially or totally block an artery cause unstable angina. If plaque in an artery ruptures or breaks open, blood clots may form. This creates a larger blockage. A clot may grow large enough to completely block the artery and cause a heart attack.
Variant (Prinzmetal's) Angina
Variant angina is rare. It usually occurs while you're at rest. The pain can be severe. It usually happens between midnight and early morning. This type of angina is relieved by medicine.
A spasm in a coronary artery causes variant angina. The spasm causes the walls of the artery to tighten and narrow. Blood flow to the heart slows or stops. Variant angina may occur in people with or without CAD.