Unstable angina pectoris has to be diagnosed if

- the intensity of symptoms increases,
- episodes of angina are of longer duration or
- occur at low levels of physical activity or even at rest.

There may also be transient ST- abnormalities in the ECG at rest.
Unstable angina may occur in untreated as well as in patients
treated with antianginal medications.
Since unstable angina may rapidly progress to acute myocardial infarction diagnosis and treatment has to be performed in these patients on an urgent or even emergency basis.