This chest tightness can change from day to day, and/or from moment to moment. All of the above combinations and variations are common. This type of chest tightness is commonly misconstrued as heart problems or the signs of a heart attack.
Cardiac arrest, also known as cardiopulmonary arrest or circulatory arrest, is a sudden stop in effective blood circulation due to the failure of the heart to contract effectively or at all. Medical personnel may refer to an unexpected cardiac arrest as a sudden cardiac arrest (SCA).
(From What is CPR? on this site)   Cardiopulmonary resuscitation (CPR) is the procedure of maintaining  artificial respiration and artificial circulation in a mammal whâ¦o  has gone into cardiac arrest through repeating cycles of chest  compressions and ventilations.