Coronary artery spasm is a temporary, sudden narrowing of one of the coronary arteries (the arteries that supply blood to the heart). The spasm slows or stops blood flow through the artery and starves part of the heart of oxygen-rich blood.

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.

A contraction of muscles in the artery wall causes these spasms in the arteries. The contraction occurs in just one area of the artery. The coronary artery may appear normal during angiography, but it does not function normally.

Coronary artery spasm affects approximately 4 out of 100,000 people. About 2% of patients with angina 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 (vasoconstriction)
• Stimulant drugs such as amphetamines and cocaine

Cocaine use and cigarette smoking can cause severe spasm 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).