What distinguishes stable angina from unstable angina?

Stable angina is characterized by its predictable nature, typically occurring during physical exertion or emotional stress when the heart's demand for oxygen increases. This predictability allows individuals to anticipate and manage their episodes, often resolving with rest or the use of nitroglycerin. In contrast, unstable angina occurs more unpredictably and can happen at rest or with minimal exertion. It can signal a worsening condition, such as a potential heart attack, as it indicates that the heart muscle is not receiving enough blood flow even in less demanding situations. This distinction in predictability is key to understanding the clinical implications and management strategies for each type of angina.