People often think that a heart attack is the same thing as a cardiac arrest. This, however, is not true. In order to understand the difference between a heart attack and a cardiac arrest, it is first necessary to understand what happens in both of these processes.

What is a heart attack?

The heart is a muscle, and like all muscles it requires an oxygen-rich blood supply. This is provided to the heart by coronary arteries. A heart attack occurs when there is a blockage of the coronary arteries. This is often caused by a blood clot. Such a blockage, if not quickly resolved, can cause parts of heart muscle to begin to die. (1-3)

What is a cardiac arrest?

A cardiac arrest is different to a heart attack. In a cardiac arrest the heart actually stops beating; whereas in a heart attack the heart normally continues to beat even though the blood supply to the heart is disrupted. (4, 5)

Symptoms of a heart attack and of cardiac arrest

In addition to the physiological mechanism being different, the symptoms of a heart attack and a cardiac arrest also vary.

Symptoms of a heart attack include:

• Chest pain – this is often a feeling of tightness in the center of the chest which may last for several minutes and will not decrease upon resting (although the most common symptom of a heart attack, not all patients having a heart attack will experience chest pain)
• Spreading of chest pain to other areas, most commonly to the arms, jaw, neck, back and abdomen
• Shortness of breath
• Coughing
• Wheezing
• Feeling or being sick
• Anxiety
• Light-headedness or dizziness
• Sweating
• Weakness
• Palpitations (noticeable heartbeats) (2, 6, 7, 8)

Symptoms of a cardiac arrest include:

• Sudden loss of consciousness/responsiveness
• No breathing
• No pulse (4, 9)

The lack of pulse is caused by the heart actually stopping during a cardiac arrest. As a consequence of this, the organs of the body are deprived of blood – this can lead to death. (13)

The following warning signs may also occur in the period before a cardiac arrest:

• Chest pain
• Shortness of breath
• Weakness
• Dizziness
• Palpitations
• Nausea (4, 10, 12)

Causes of heart attacks and cardiac arrests

Cardiac arrests have several potential causes. These include:

• Ventricular fibrillation – an abnormal heart rhythm (arrhythmia) where the lower chambers of the heart (the ventricles) beat irregularly
• Ventricular tachycardia
• Coronary heart disease
• Changes of the heart structure
• Pacemaker failure
• Respiratory arrest
• Choking
• Drowning
• Electrocution
• Hypothermia
• Dramatic drop in blood pressure
• Drug abuse
• Excessive alcohol consumption
• An unknown reason (4, 5, 13)

A cardiac arrest can also be caused by a heart attack. (5) In fact, according to the British Heart Foundation, the majority of cardiac arrests in the UK are caused by heart attacks. (18)

A heart attack itself involves a cut off in the blood supply to part of the heart muscle. If a large enough portion of the heart is affected, then the heart may stop beating, i.e. a cardiac arrest may occur. (14)

But what about heart attacks themselves? What causes them? Well, in contrast to cardiac arrests, heart attacks are generally caused by one main factor – coronary heart disease (CHD). (14) CHD is a condition that is generally caused by fatty deposits building up in the coronary arteries, which provide oxygenated blood to the heart. This is also known as atherosclerosis. (15 -17) Those most at risk of CHD include:

• Smokers
• Those who eat an unhealthy diet – one that is high in saturated fat
• Those with high blood pressure
• Those with diabetes
• Overweight or obese people
• People who do not exercise frequently
• Older people, in particularly older men
• Those with a family history of heart disease
• People who have been exposed to air pollution, particularly traffic pollution (14, 17)

People with CHD may experience a heart attack if a plaque, (a raised patch on the artery wall) splits and causes a blood clot which in turn blocks the coronary artery. (17)

Summary

In summary, there is a difference between a heart attack and a cardiac arrest. A heart attack occurs when the blood supply to part of the heart stops and thus causes a section of the heart muscle to begin to die; whereas a cardiac arrest occurs when the heart stops beating as a whole. There are various symptoms of a heart attack. In contrast, the main symptoms of a cardiac arrest are unconsciousness, lack of breathing and no pulse. Finally, there are many different causes of a cardiac arrest; whereas the main cause of a heart attack is coronary heart disease.