Key Difference: Cardiac Arrest is a heart condition where the heart does not contract properly, thereby failing to effectively circulate blood to the other organs. Cardiac arrest brought on suddenly is known as Sudden Cardiac Arrest (SCA) and causes the heart to stop beating completely.

Cardiac arrest and sudden cardiac arrest are just two sides of the same coin. They are essentially the same condition that occurs in a different way. Sudden cardiac arrest is exactly the same as a cardiac arrest, with the only difference being that it occurs suddenly and without warning.

Cardiac Arrest is a heart condition where the heart does not contract properly, thereby failing to effectively circulate blood to the other organs. Cardiac arrest is brought on by irregular beating of the heart that causes it to stop supplying blood flow to the other organs, including the brain. Cardiac arrest is also known as cardiopulmonary arrest or circulatory arrest. The heart has an internal electrical system that allows it to control the rhythm of the heart; any changes to the rhythm can cause the heart to either beat too fast, too slow or stop beating completely. These changes are known as arrhythmias. The lack of blood flow leaves the other organs starved for oxygenated blood. The lack of oxygen to the brain causes the person to faint. If the person does not receive help during the first five minutes of fainting, it can result in permanent damage to the brain.

Cardiac arrest can be a cause of Coronary heart disease, cardiac abnormalities such as cardiomyopathy, cardiac rhythm disturbances, hypertensive heart disease, congestive heart failure, etc., trauma, overdose, drowning, smoking, obesity, lack of physical exercise, etc. Cardiac arrest differs from heart attack as in a heart attack, the heart does not receive the oxygenated blood and all the while it continues to beat and pump until the cells die completely. In cardiac arrest, the heart itself stops beating, though it still receives constant supply of oxygenated blood.

Symptoms of cardiac arrest include fainting and loss of pulse or heartbeat. The person stops breathing as the heart no longer pumps. The person that suffers a cardiac arrest must receive quick cardiopulmonary resuscitation (CPR) to keep the heart pumping the brain from losing cells. The longer it takes the person to receive help, the more chances that they may have loss of memory, brain damages or less chances of survival. Defibrillation (or shocking the heart) is another way to revive the heart. Implantable cardioverter-defibrillators (ICDs) and pacemakers are used to ensure that the person does not suffer from another cardiac arrest episode in the event of arrhythmia.

Sudden cardiac arrest is nothing but a cardiac arrest that was surprising. Sudden cardiac arrests are when the heart loses pumping function unexpectedly. More commonly, sudden cardiac arrests happen during a heart attack, when the heart unexpectedly stops pumping blood. Defibrillators and CPR are used revive the patient. Sudden cardiac arrest is a medical emergency and if not treated immediately could cause sudden cardiac death. 

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