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 most often is felt under the chest bone (sternum) or left side of the chest, 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 of coronary artery spasm:
--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

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