Sudden Cardiac Arrest is not a heart attack
Sudden cardiac arrest (SCA) is often confused with a heart attack. A prior heart attack increases one's risk for SCA, but SCA is quite different from a heart attack. Both disorders stem from problems with the heart but each with distinct risk factors, treatment options, and outcomes.
Anatomy of a Heart Attack
A heart attack or myocardial infarction is caused by a circulation or plumbing problem of the heart, when one (or more) of the arteries delivering blood to the heart is blocked. Oxygen in the blood cannot reach the heart muscle, and the heart muscle becomes damaged.
This damage to the heart muscle can lead to disturbances of the heart's electrical system. And a malfunction of the heart's electrical system may cause dangerously fast heart rhythms that can lead to SCA.
Substrate of Sudden Cardiac Arrest
In contrast to a heart attack, sudden cardiac arrest (SCA) is usually caused by an electrical problem in the heart.
SCA occurs when the heart's lower chambers (ventricles) suddenly develop a rapid, irregular rhythm (ventricular fibrillation (VF)) causing the ventricles to quiver rather than contract.
The chaotic quivering motion of the ventricles renders the heart an ineffective pump that can no longer supply the body and brain with oxygen.