What is angina?
Angina is chest pain or discomfort you get when your heart muscle does not get enough blood. Angina, also called angina pectoris ("pectoris" means chest) is classified by type.

Types of angina
There are three types of angina: stable, unstable and variant. Unstable angina is the most dangerous and is a sign that you could have a heart attack soon.

1. Stable angina - Stable angina occurs when the heart works harder than usual and follows a regular pattern. This type of angina is characterized by persistent, recurring chest pain that usually occurs with exertion and is the most common type of angina. However, stable angina makes a heart attack more likely in the future.
2. Unstable angina - Unstable angina is a sudden, new chest pain or a change in the pattern of previously stable angina that may signal an impending heart attack. Unstable angina doesn't follow a pattern and can occur with or without physical exertion and isn't relieved by rest or medicine. Unstable angina is very dangerous and needs emergency treatment as it is a sign that a heart attack may happen soon.
3. Variant angina - A third, a rare type of angina called variant angina (Prinzmetal's angina) is caused by a coronary artery spasm. Variant angine usually occurs while at rest.

Angina can be triggered.  And it can be avoided.  Who is at risk of developing angina?  And what causes angina pectoris?  More information on risk factors and causes of angina in the section that follows.