While these two terms are used quite interchangeably, they denote different medical events. A heart attack (myocardial infarction) is a circulation problem that involves blood flow being blocked from reaching the heart. During cardiac arrest, an electrical problem causes the heart to stop beating and needs to be restarted.

We’ve all heard these terms at one point or another. Because they’re both serious conditions and quite similar in symptoms, we also tend to lump them together and treat them as synonyms. That being said, however, they are not the same thing, and they are not interchangeable.

So let’s dive into the differences between them.

Heart attacks

These occur when one of the coronary arteries supplying oxygenated blood to a section of the heart gets blocked. If this blockage isn’t cleared quickly, cells in the affected area of the heart start dying due to a lack of oxygen. This effect builds up over time so the longer an individual goes without treatment, the more damage accumulates in tissues in that part of their heart.

Blockages are typically caused by build-ups of fat, either cholesterol (that’s why your doctor is so insistent you lower it), or a series of other substances.

While symptoms can definitely be immediate and intense (such as feelings of pressure, tightness, or intense pain in the chest), they can also occur over time, up to weeks in advance of an actual heart attack. There is also quite a large degree of variation in regards to the symptoms of various patients. Women can have different symptoms than men; some patients have no symptoms at all. Angina (recurrent chest pain or pressure) triggered by physical activity and relieved by stress is the most common and earliest warning sign of heart attack.

That being said, it’s important to act quickly in case you’re experiencing these symptoms or think you’re having a heart attack. Call emergency services even if you’re not sure you’re having a heart attack, as every minute matters. Emergency services personnel can begin treatment the moment when they arrive; getting to the hospital by yourself would take a lot longer. They can also provide resuscitation in case a patient’s heart has stopped completely.

Cardiac arrest

Unlike a heart attack, cardiac arrest occurs suddenly and very often without warning. It involves an abrupt loss of heart function and can be extremely dangerous.

It is caused by an electrical malfunction in the heart which produces arrhythmia (irregular heartbeat). Due to this disruption, blood flow to the brain, lungs, and other organs is disrupted — and with it, the flow of oxygen as well. The lack of oxygen supply to the brain can render a person unconscious in mere seconds and stop heart function completely. Victims of cardiac arrest can die within minutes without treatment.

Symptoms of cardiac arrest include dizziness, loss of consciousness, and shortness of breath. Cardiac arrest events can happen in individuals who may or may not have been diagnosed with heart disease. It may be reversed, however, if CPR is performed on the patient, and a defibrillator is used to restore a normal heart rhythm within a few minutes.

If someone near you is experiencing cardiac arrest, first call emergency services. Then, get an automated external defibrillator (AED) if one is available; if not, begin performing CPR on the patient. If two people are available, one should begin CPR immediately, while the other handles the call and retrieves an AED. If AED solutions are available, they must be used as quickly as possible.

It may be needed that you perform CPR on the patient for a longer period of time. If that’s the case, don’t worry. Hands-only CPR to the beat of “Stayin’ Alive” can double or even triple a victim’s chances of survival — hang in there!