What is a heart attack?
A heart attack occurs when a blocked artery prevents oxygen-rich blood from reaching a section of the heart.  If the blocked artery is not reopened quickly, the part of the heart normally nourished by that artery begins to die.  The longer a person goes without treatment, the greater the damage.  Symptoms of a heart attack may be immediate and intense.  More often, though, symptoms start slowly and persist for hours, days or weeks before a heart attack.  Unlike with sudden cardiac arrest, the heart usually does not stop beating during a heart attack.  The heart attack symptoms in women can be different than men.

What is cardiac arrest?
Sudden cardiac arrest occurs suddenly and without warning.  It is triggered by an electrical malfunction in the heart that causes an irregular heartbeat.  With its pumping action disrupted, the heart cannot pump blood to the brain, lungs and other organs.  Seconds later, a person loses consciousness and has no pulse.  Death occurs within minutes if the victim does not receive treatment.

What is the link?
These two distinct heart conditions are linked.  Sudden cardiac arrest can occur after a heart attack, or during recovery.  Heart attacks increase the risk for sudden cardiac arrest.  Most heart attacks do not lead to sudden cardiac arrest.  But when sudden cardiac arrest occurs, heart attack is a common cause.  Other heart conditions may also disrupt the heart's rhythm and lead to sudden cardiac arrest.  These include a thickened heart muscle, heart failure, and arrhythmias.