Middle-age patients who experience moderate to severe angina (grading by classes II, III, and IV) have a five-year survival rate of approximately 92%. Classification
Stable angina
Also known as effort angina, this refers to the classic type of angina related to myocardial ischemia. A typical presentation of stable angina is that of chest discomfort and associated symptoms precipitated by some activity (running, walking, etc.) with minimal or non-existent symptoms at rest or after administration of sublingual nitroglycerin. Symptoms typically abate several minutes after activity and recur when activity resumes. In this way, stable angina may be thought of as being similar to intermittent claudication symptoms. Other recognized precipitants of stable angina include cold weather, heavy meals, and emotional stress. Unstable angina
Unstable angina (UA) (also "crescendo angina"; this is a form of acute coronary syndrome) is defined as angina pectoris that changes or worsens.It has at least one of these three features:

it occurs at rest (or with minimal exertion), usually lasting more than 10 minutes
it is severe and of new-onset (i.e., within the prior 4–6 weeks)
it occurs with a crescendo pattern (i.e., distinctly more severe, prolonged, or frequent than before).UA may occur unpredictably at rest, which may be a serious indicator of an impending heart attack. What differentiates stable angina from unstable angina (other than symptoms) is the pathophysiology of the atherosclerosis. The pathophysiology of unstable angina is the reduction of coronary flow due to transient platelet aggregation on apparently normal endothelium, coronary artery spasms, or coronary thrombosis.
References
External links
Treatment of stable angina recommendations for patients in laymans terms
British Heart Foundation - Angina
Angina Pectoris Animation Video 3D
Guidelines on the management of stable angina pectoris - European Society of Cardiology
Heart Attack and Angina Statistics by American Heart Association: Final 2006 statistics for the United States