It is usually a symptom of coronary artery disease, which occurs when fatty deposits accumulate on the walls of the arteries of the heart, obstructing blood flow and reducing oxygen availability to heart muscle. Angina pain can also be a symptom of heart valve problems. Stable or typical angina is generally defined as sudden onset of intense but temporary chest pain or feeling of pressure on the chest, often but not always triggered by stress, physical exertion or excitement. Pain may also show up in the left shoulder or inside the left arm. Episodes of stable angina are often worse after a meal or in cold weather.
Unstable angina is the most dangerous.
In this form, the pattern of symptoms changes without notice, reflecting a rapid progression of coronary artery disease. This constriction can be caused by cocaine use or by spasms of the large coronary arteries. These spasms that restrict blood flow in the large coronary arteries cause Prinzmetal's or variant angina. The ECG tracings for the two forms are also different. It often affects women under the age of 50 and characteristically occurs in the early morning, awakening people from sleep.