Clinical Definition

Unstable angina is a cardiac condition, causing acute chest pain. The chest pain occurs due to decreased blood flow to the myocardium. The most common underlying cause of unstable angina is atherosclerosis. Unstable angina characteristically does not have a pattern and may occur without physical exertion.

In Our Own Words

Unstable angina is a sign that you might be having a heart attack or that a heart attack might happen soon, so treat it as an emergency. It is new or increasing chest pain, which comes on suddenly, usually due to a blockage and lack of oxygen to the heart. It differs from stable angina. Stable angina may come on during physical activity when the heart is working harder. Unstable angina can occur at rest. Pain is also often more severe with unstable angina compared to stable angina. Unstable angina is most often caused by a ruptured plaque in a coronary artery. This atherosclerotic plaque, which is fatty material, can build up, rupture, and clot within the arteries, blocking or significantly reducing blood flow.