What is the defining characteristic of Prinzmetal angina?

Prinzmetal angina, also known as variant angina, is characterized primarily by episodes of chest pain that occur at rest, commonly due to coronary artery spasm. This condition is often associated with transient ST segment elevation on an electrocardiogram (ECG) during episodes of pain. The ST segment changes are indicative of myocardial ischemia that stems from the reduced blood flow caused by the temporary spasms of the coronary arteries.

Unlike typical angina, which usually occurs during physical exertion or emotional stress (options A and C), Prinzmetal angina can manifest spontaneously, particularly during rest or even during sleep. The nature of the pain and the associated ST segment changes are crucial for diagnosis. While it is vital to recognize that Prinzmetal angina can be triggered by various factors, including stress or smoking, its defining characteristic remains the occurrence of chest pain at rest paired with the ST segment shifts observed during these episodes. Hence, option B stands out as the defining characteristic.

In contrast to the notion that it always leads to heart failure (option D), while Prinzmetal angina can be concerning and require management, it does not inherently result in heart failure in every case. Thus, the defining characteristics are primarily related to