Angina:

Any attack of painful spasms characterized by sensations of choking or suffocating. Angina Pectoris is a constricting pain below the sternum, often precipitated by exertion or excitement and caused by ischemia of the heart muscle, usually due to a coronary artery disease. There are more than 6.3 million angina sufferers in the US. Angina is said to be Stable when the victim is able to predict a pattern of physical activity likely to cause an attack and Unstable when attacks are unpredictable and difficult to control.