Heart Attack or Sudden Cardiac Arrest?

The term "heart attack" often is used interchangeably with "sudden cardiac arrest" but they actually are two different things. So what's the difference and why does it matter?

Sudden Cardiac Arrest
Sudden cardiac arrest occurs when the heart suddenly stops beating. This happens when something disturbs the regular rhythm of heart (for example, a thickened heart muscle, structural defects, myocardial infarction or coronary artery disease). The heart quits pumping blood to the brain and the victim quickly loses consciousness. Death occurs if the heart does not resume pumping quickly. This is where you take action by delivering CPR and defibrillation.

Heart Attack
The term "heart attack" is a popular substitute for a medical condition called myocardial infarction--this is where blood flow in the coronary arteries to the heart is blocked. The lack of blood causes permanent damage to the tissues in the affected areas of the heart. Myocardial infarction may lead to fatal heart rhythms when the tissue damage is bad enough that it disturbs the normal electrical activity of the heart, however most do not lead to sudden cardiac arrest.

To add to the confusion the word "heart attack" is generally used in our culture as an all-encompassing term to imply something bad that happens to the heart. This can mean anything from a twinge of chest pain to sudden cardiac arrest.

Summary
Imprecise use of the terms heart attack and sudden cardiac arrest can cause confusion about how serious a problem a person is experiencing. In a general sense, a heart attack. Sudden cardiac arrest means the heart has stopped (and death is imminent). Heart attack means blood flow to the heart has damaged an area of heart muscle (serious but usually no imminent death).

The terms don't mean the same thing and both require very different treatment.

Additional Information

View animation of irregular heart rhythms (external website)