Prinzmetal's angina is typically characterized by:

Prinzmetal's angina, also known as variant angina, is primarily characterized by episodes of chest pain resulting from spasms in the coronary arteries. These spasms can occur suddenly and often happen at rest, typically during periods of stress or at night. The pain associated with Prinzmetal's angina is a result of reduced blood flow due to these spasms, which can temporarily decrease oxygen supply to the heart muscle, leading to angina symptoms.

Understanding the nature of the spasms is crucial; they can be associated with underlying conditions such as coronary artery disease but can also occur in otherwise healthy individuals, particularly in those with risk factors like smoking or stress. The description of the spasms as "cramps" is fitting, as they can be transient and often resolve spontaneously.

The other choices do describe possible cardiac conditions but do not align with the defining characteristics of Prinzmetal's angina. Irregular heart rates or rapid contractions pertain to other dysrhythmias and physical conditions that are not specific to the spasmodic nature of Prinzmetal's angina. Additionally, the thickening and hardening of blood vessels describes atherosclerosis rather than the spasms typical of this variant angina.