A nurse is caring for a client in a cardiac unit. The client presents with intermittent chest discomfort that varies in intensity and duration. The nurse conducts an assessment to gather pertinent clinical information. Based on the clinical findings, which characteristics are consistent with unstable angina or stable angina.

Angina occurs due to myocardial ischemia from reduced coronary blood flow, but the pattern, triggers, and response to rest or medication help distinguish its severity. Stable angina is predictable and relieved with rest, while unstable angina is more dangerous, occurs unpredictably (often at rest), and is part of acute coronary syndrome. Recognizing unstable angina is critical because it can progress to myocardial infarction. Rationale: • Chest pain that occurs at rest and increases in severity and duration over time: Pain at rest with increasing frequency and intensity is a hallmark of unstable angina. It indicates worsening coronary artery obstruction and reduced myocardial oxygen supply. This pattern reflects acute coronary syndrome and is not predictable or activity-related. It requires urgent evaluation due to high risk of infarction. • Chest pain triggered by physical activity and relieved by rest or nitroglycerin: Stable angina is caused by predictable myocardial oxygen demand during exertion. It occurs with activity and resolves with rest or nitroglycerin, which improves coronary perfusion. The pattern is consistent over time and does not typically worsen rapidly. This makes it distinguishable from unstable angina. • Pain typically resolves within minutes and does not require emergent medical attention: Stable angina episodes are brief and self-limiting once the triggering activity stops. The pain usually lasts only a few minutes and is relieved by rest or medication. It does not represent immediate myocardial injury. Therefore, it is not considered an emergency condition. • May progress to myocardial infarction if not treated promptly: Unstable angina reflects plaque rupture and partial coronary artery occlusion, placing the client at high risk for complete blockage. Without treatment, it can rapidly progress to myocardial infarction. It is considered a medical emergency within the spectrum of acute coronary syndrome. Early recognition and intervention are essential to prevent myocardial damage.