What is the main characteristic of variant (Prinzmetal) angina?

The main characteristic of variant (Prinzmetal) angina is unpredictable episodes of chest pain that typically occur at rest, often during the night or early morning hours. This type of angina is caused by coronary artery spasm, which leads to temporary narrowing of the arteries and reduced blood flow to the heart muscle. Unlike typical exertional angina, which is often triggered by physical activity or emotional stress, variant angina can strike without any obvious precipitating factors. This unpredictability in timing and circumstances is a key feature that differentiates it from other forms of angina.

In contrast, episodes of exertional angina occur primarily during physical activity due to increased myocardial oxygen demand. The relief of chest pain with nitroglycerin is commonly associated with stable angina rather than specifically indicative of variant angina, although it can still provide relief in this type. Aging-related pain does not specifically define variant angina and encompasses a broader range of age-associated ailments, making it less relevant in distinguishing the unique characteristics of Prinzmetal angina.