A coronary artery spasm is a temporary tightening (constriction) of the muscles in the wall of one of the arteries that sends blood to your heart. A spasm can decrease or completely block blood flow to part of the heart.

If a spasm lasts long enough, you can have chest pain (angina) and even a heart attack (myocardial infarction). Unlike typical angina, which usually occurs with physical activity, coronary artery spasms often occur at rest, typically between midnight and early morning.

Other names for coronary artery spasms are Prinzmetal's angina, vasospastic angina or variant angina.

Many people who have coronary artery spasms don't have common risk factors for heart disease, such as high cholesterol and high blood pressure. But they're often smokers. You can reduce your risk of coronary artery spasms by quitting smoking.

Coronary artery spasms may be triggered by:

• Tobacco use
• Exposure to cold
• Extreme emotional stress
• Use of illegal stimulant drugs, such as amphetamines and cocaine

Treatment of coronary artery spasms may include medications such as:

• Nitrates, which are used to prevent spasms and quickly relieve chest pain as it occurs
• Calcium channel blockers, which relax the arteries and decrease the spasm
• Statin medications, which not only lower cholesterol but also may prevent spasms

If coronary artery spasms result in a dangerously fast heartbeat (ventricular arrhythmia), your doctor may recommend an implantable cardioverter-defibrillator (ICD). An ICD uses electric impulses to restore a normal heartbeat and prevent sudden cardiac death.

If you're having sudden chest pain, call 911 or emergency medical help immediately.