Which of the following is a key clinical manifestation of unstable angina?

B. Chest pain at rest is indeed a key clinical manifestation of unstable angina. Unstable angina is characterized by unpredictable chest pain that can occur at rest or with minimal exertion, and it signifies a potential worsening of coronary artery disease. This type of angina is concerning because it suggests that the heart muscle is not receiving enough blood, which may eventually lead to a heart attack if not addressed.

In contrast, other manifestations like chest pain with a stable pattern would indicate stable angina, where pain typically follows a predictable pattern and occurs with exertion but is relieved by rest or medication. Chest pain that improves with rest suggests a stable angina scenario, where the pain subsides after cessation of activity. Lastly, having no chest discomfort at all does not align with unstable angina, as the presence of pain, especially at rest, is a significant marker of this condition. Understanding these distinctions is crucial for identifying and managing unstable angina effectively.