What is angina pectoris that occurs at rest without a precipitating event known as?

Angina pectoris that occurs at rest without a precipitating event is known as unstable angina. This condition is indicative of an underlying problem with the heart's blood supply, as it occurs unpredictably and is often more severe than stable angina, which typically happens during exertion or stress. Unstable angina is a critical warning sign of increased risk for heart attack and requires immediate medical attention.

In contrast, stable angina is characterized by predictable patterns of chest pain that occur with exertion and are relieved by rest or medication. Variant angina, also known as Prinzmetal angina, is caused by temporary spasms in the coronary arteries and usually occurs at rest, but it is distinct from unstable angina due to its predictable episodes related to coronary vessel constriction. Mitral angina is not a commonly recognized term in cardiology and does not refer to a specific form of angina. Therefore, unstable angina is the most accurate description of angina that occurs at rest without a precipitating event.