Which statement accurately describes the relationship between stable and unstable angina?

• A. It is reclassified from stable angina when symptoms worsen.
• B. It is the same as stable angina.
• C. It never requires hospitalization.
• D. Troponin is always elevated.

Answer: (A)

Unstable angina represents a change from stable angina in which symptoms worsen or occur at rest, or there is a new or more frequent/intense pattern of chest pain. When this happens, the condition is reclassified as unstable angina, part of the acute coronary syndrome spectrum.

In stable angina, chest pain is predictable with exertion and relieved by rest or nitroglycerin, due to a fixed atherosclerotic plaque causing reversible ischemia. Unstable angina results from a rupture of a plaque with thrombosis, leading to new or worsening ischemia that can occur even at rest. The key distinction is this change in pattern and the implication that it may progress to myocardial infarction if not treated; troponin levels may be normal in unstable angina, whereas they rise if myocardial injury occurs (NSTEMI or STEMI). This is why the statement about reclassification is the best description of their relationship.