The nurse knows which of the following types of angina is most closely related with an impending myocardial infarction?

A. Variant angina (Prinzmetal’s) is caused by coronary artery spasm and is less directly linked to MI. B. Chronic stable angina occurs predictably with exertion and is less associated with immediate MI risk. C. Unstable angina signals worsening coronary artery disease and often precedes a myocardial infarction. D. Nocturnal angina is less common and not specifically predictive of MI.