Final answer:
The two subclasses of typical angina are stable angina and unstable angina. Stable angina occurs with exertion and improves with rest, while unstable angina occurs at rest and requires immediate medical attention.
Step-by-step explanation:
There are two subclasses of typical angina: stable angina and unstable angina. Stable angina occurs when pain is triggered by exertion and improves with rest or nitroglycerin administration.
Unstable angina, on the other hand, is characterized by pain that occurs at rest, lasts more than 15 minutes, and is of new onset.
Unstable angina is more dangerous and requires immediate medical attention as it could be a sign of an impending heart attack.