The spasm often occurs in coronary arteries that have not become hardened due to plaque buildup (atherosclerosis). However, it also can occur in arteries with plaque buildup. These spasms are due to a squeezing of muscles in the artery wall. They usually occur in just one area of the artery. The coronary artery may appear normal during testing, but it does not function normally. About 2% of patients with angina (chest pain and pressure) have coronary artery spasm. Coronary artery spasm occurs most commonly in people who smoke or who have high cholesterol or high blood pressure. It may occur without cause, or it may be triggered by:
--Alcohol withdrawal
--Emotional stress
--Exposure to cold
--Medications that cause narrowing of the blood vessels
--Stimulant drugs, such as amphetamines and cocaine

Cocaine use and cigarette smoking can cause severe spasms of the arteries, and can cause the heart to work harder. In many people, coronary artery spasm may occur without any other heart risk factors (such as smoking, diabetes, high blood pressure, and high cholesterol).