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).

Spasm may be "silent" -- without symptoms -- or it may result in chest pain or angina. If the spasm lasts long enough, it may even cause a heart attack.

The main symptom is a type of chest pain called angina, which can be felt under the chest bone and is described as:

• Constricting
• Crushing
• Pressure
• Squeezing
• Tightness

It is usually severe. The pain may spread to the neck, jaw, shoulder, or arm.

The pain:

• Often occurs at rest
• May occur at the same time each day, usually between midnight and 8:00 AM
• Lasts from 5 to 30 minutes

The person may lose consciousness.

Unlike angina that is caused by hardening of the coronary arteries, chest pain and shortness of breath are often not present when you walk or exercise.

Tests to diagnose coronary artery spasm may include:

• Coronary angiography
• ECG

The goal of treatment is to control chest pain and prevent a heart attack. A medicine called nitroglycerin can relieve an episode of pain.

Your health care provider may prescribe other medications to prevent chest pain. You may need a group of medicines called calcium channel blockers long-term. Your doctor may prescribe long-acting nitrates along with the calcium channel blockers.

Beta-blockers are another type of medication that may be used. However, in some cases, beta-blockers may be harmful (especially if used along with cocaine).

Coronary artery spasm is a chronic condition. However, treatment usually helps control symptoms.

The disorder may be a sign that you have a high risk for heart attacks or potentially deadly irregular heart rhythms (arrhythmias). The outlook is generally good if you follow your doctor's treatment recommendations and avoid certain triggers.

• Abnormal heart rhythms, which may cause cardiac arrest and sudden death
• Heart attacks

Immediately call your local emergency number (such as 911) or go to the hospital emergency room if you have a history of angina and the crushing or squeezing chest pain is not relieved by nitroglycerin. The pain may be due to a heart attack. Rest and nitroglycerin do not completely relieve the pain of a heart attack.

A heart attack is a medical emergency. If you have symptoms of a heart attack, seek immediate medical help.

Prevention involves avoiding triggers and taking measures to reduce your risk of atherosclerosis. This may include eating a low-fat diet and increasing exercise.

If you have this condition, you should avoid exposure to cold, cocaine use, cigarette smoking, and high-stress situations, which can trigger a spasm.

Cannon CP, Braunwald E. Unstable angina and non-ST elevation myocardial infarction. In: Libby P, Bonow RO, Mann DL, Zipes DP, eds. Libby: Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 8th ed. Saunders; 2007:chap 53.