Coronary artery spasm: A spasm (a sudden constriction) of one of the coronary arteries depriving the (myocardium (the heart muscle) of blood and oxygen. This can cause chest pain referred to as variant (or Prinzmetal's) angina.

Coronary artery spasm can be triggered by emotional stress, medicines, street drugs (such as cocaine) or exposure to cold.

Treatments include beta-blocker medications and, classically, nitroglycerin is prescribed to permit the coronary arteries to open up (dilate). Illicit drug use should be discontinued and stress reduced, if possible.