Cardiac Arrest Symptoms, Causes, and Risk Factors

A man having a heart attack
  • Sudden cardiac arrest (SCA) is a critical medical emergency that occurs when the heart stops functioning completely.

  • The primary symptoms of cardiac arrest include suddenly falling unconscious, no heartbeat, and not breathing.

  • Cardiac arrest can be caused by various heart conditions, including coronary artery disease (CAD) and some arrhythmias.

  • Risk factors for cardiac arrest include excessive alcohol consumption, smoking, obesity, and high blood pressure.

  • If you suspect that someone is experiencing cardiac arrest, you must call 911 for emergency medical assistance.

Cardiac arrest is a serious health condition that could result in sudden cardiac death if not treated urgently.

According to data from the Centers for Disease Control and Prevention (CDC), over 365,000 people in the U.S. suffer from cardiac arrest each year. About 80% of these cases result in death before the patients can be admitted to hospital.

If you or somebody you know is experiencing symptoms of cardiac arrest, you should contact 911 immediately. Begin CPR or use a device called an automated external defibrillator (AED) if it’s available.

What is Sudden Cardiac Arrest?

Sudden cardiac arrest is when the heart stops functioning completely. This immediate loss of all heart activity results from an abnormal heart rhythm.

When the heart stops working, blood flow to the brain and other organs is interrupted, which may cause serious complications such as:

  • Brain damage

  • Organ failure

  • Impaired cardiac function

  • Sudden death (in extreme cases)

The problem with the heart’s electrical system and rhythm is typically not detectable leading up to cardiac arrest, which is why the onset is sudden.

Key Point: The Difference Between a Heart Attack and SCA

Many people assume that a heart attack and sudden cardiac arrest are the same thing. However, there are two distinct conditions.

A heart attack is when the blood flow to a part of the heart is blocked. Sudden cardiac arrest, on the other hand, is not typically due to any blockages.

However, a heart attack can change the heart’s rhythm and electrical system, which can lead to sudden cardiac arrest.

What are the Symptoms of Cardiac Arrest?

Symptoms of this condition occur suddenly, often without warning. The main symptoms of cardiac arrest include:

Sudden collapse

The main indicator of sudden cardiac arrest is an abrupt collapse, which occurs as the heart stops pumping blood to the brain and other parts of the body.

No pulse

If someone has no pulse or heartbeat, they may be experiencing sudden cardiac arrest. In this condition, the pumping action of the heart comes to a stop, meaning there won’t be any detectable pulse.

No breathing

When the heart stops functioning, the lungs no longer receive oxygen-rich blood.

Without oxygenated blood, the respiratory system can fail, possibly causing breathing to stop, with occasional gasping breaths observed in affected individuals.

Loss of consciousness

With no oxygen reaching the brain or body, individuals undergoing cardiac arrest can quickly lose consciousness and become unresponsive.

Loss of consciousness typically occurs within a few seconds to a minute after cardiac arrest begins.

Symptoms That May Occur Before Cardiac Arrest

In some cases, individuals may experience certain symptoms before cardiac arrest. These can include:

  • Chest pain

  • Shortness of breath

  • Weakness

  • Heart palpitations

  • Dizziness

  • Nausea

It’s important to note that the above symptoms are commonly associated with a heart attack, which could happen before cardiac arrest.

Causes of Sudden Cardiac Arrest

The following heart conditions can cause sudden cardiac arrest:


An arrhythmia is an abnormal heart rhythm. It usually occurs when the electrical signals in the heart are disrupted.

Ventricular fibrillation is one such arrhythmia and it is the most common cause of cardiac arrest.

This condition is characterized by a rapid heartbeat within the heart's ventricles, which hinders its ability to pump blood effectively.

Coronary artery disease (CAD)

This is a heart condition where the coronary arteries — the blood vessels that supply oxygen and nutrients to the heart muscle — become narrowed or blocked.

The blockage is often caused by a buildup of plaque in the artery walls. This plaque can be a combination of fat, cholesterol, and calcium.

The narrowing or blockage of the arteries can reduce blood flow to the heart muscle, which may potentially result in sudden cardiac arrest.

Heart attack

This condition can have a significant impact on the structure of the heart as well as its function and electrical system.

Damage to the heart and its diminished pumping efficiency can result in abnormal heart rhythms. These life-threatening arrhythmias may lead to cardiac arrest.

An enlarged heart

Also known as cardiomyopathy, an enlarged heart occurs when the walls in the heart muscle stretch, making the muscle bigger and thicker.

This can make it harder for the heart to pump blood and disrupt the organ’s normal electrical pathways, potentially leading to sudden cardiac arrest.

Heart valve disease

This condition is characterized by the heart valves either leaking or narrowing, which can lead to the heart muscle becoming thickened or stretched.

When the heart’s chambers are enlarged or weakened due to stress caused by a contracted valve, there’s an increased risk of arrhythmias that can cause cardiac arrest.

Congenital heart defects (CHDs)

A congenital heart defect refers to a condition present at birth that impacts the heart's structure and can interfere with its natural electrical system.

This can affect the delivery of oxygen and blood to the heart muscle.

The stress placed on the heart due to CHD can lead to cardiac arrest. Patients who have received surgery for CHD are more at risk for cardiac arrest.

Risk Factors for Sudden Cardiac Arrest

Certain individuals have a higher chance of experiencing cardiac arrest. Risk factors for this condition include:

Alcohol and drug use

These substances impact the cardiovascular system. Excessive alcohol consumption, for example, can weaken the heart and cause it to not pump blood efficiently.

This weakened state can lead to heart failure and arrhythmia, increasing the risk of cardiac arrest.

Family history

Certain genetic factors can predispose individuals to heart-related conditions, such as coronary artery disease and some arrhythmias.

If these conditions are present in family members, especially in your close relatives, your risk of cardiac arrest increases.

Heart disease

Heart disease impacts the structure and function of the heart in several ways. Heart conditions that may lead to cardiac arrest include:

  • Cardiomyopathy

  • Heart valve disease

  • Coronary artery disease (CAD)

  • Electrical system disorders such as Long QT Syndrome (LQTS)

High blood pressure

Also known as hypertension, high blood pressure has a long-term effect on the cardiovascular system. It can lead to heart conditions such as hypertrophy, CAD, heart attack, and heart failure. These conditions can all result in cardiac arrest.

High cholesterol

High cholesterol is another potential cause of CAD and other heart conditions. This is because cholesterol forms plaque in the arteries, which can harden and narrow these vessels, which in turn diminishes blood flow to the heart.

The damage this causes to the heart and its electrical system can lead to cardiac arrest.


Excess body weight has a significant impact on how the heart functions. Obesity increases the demand on the heart to pump blood to a larger body mass. This increased workload can lead to an enlargement of the heart muscle, which could eventually cause cardiac arrest.


A chemical in cigarettes called nicotine stimulates the sympathetic nervous system, which can increase both your heart rate and blood pressure.

This puts additional strain on the heart and can damage it over time.

Additionally, the carbon monoxide in cigarettes reduces the oxygen-carrying capacity of the blood, meaning the heart must work harder to supply oxygen to the body.

Over time, this can lead to the weakening of the heart and cardiac arrest.

Emergency Treatment for Cardiac Arrest

Even if you only have mild symptoms, it’s important that you seek immediate treatment if you or someone you know is experiencing cardiac arrest.

This is a serious condition that must be treated immediately.

Cardiopulmonary resuscitation (CPR)

In most cases, the initial treatment for cardiac arrest involves CPR, where chest compressions are administered to increase blood flow to the heart and other vital organs.

CPR can temporarily treat sudden cardiac arrest until more advanced medical treatment is available.

A defibrillator

In some states, there is a requirement for AEDs to be available in all public spaces. This device is similar to a defibrillator and can deliver electrical shock to the heart.

Once you have called 911 and emergency personnel arrive, they will use a defibrillator to help the heart start beating again.

This treatment is designed to save the person’s life and reduce the chances of organ damage due to the lack of oxygen.

Recovery After Cardiac Arrest

After surviving sudden cardiac arrest, you’ll be admitted to a hospital to receive ongoing care.

Your medical team will monitor your heart and administer medications that can help to reduce the risk of another sudden cardiac arrest. They’ll also run tests to determine the cause of your SCA.

Recovery from cardiac arrest looks different from one person to the next and will depend on how long the individual is without oxygen and any permanent damage to the organs.

Where Can I Learn More About Heart Health?

With LifeMD, you can connect with a board-certified physician or nurse practitioner to discuss any concerns you may have about your heart health.

A team of medical professionals can provide treatment plans for heart conditions and make recommendations to reduce your cardiac arrest risk factors.

Make an appointment today to get started.

Jennifer McMillan, APRN, FNP-BC

Jennifer is a board-certified, multistate licensed Nurse Practitioner with over 25 years experience in healthcare. She specializes in Women and Men’s Health, Psychiatry, and Urgent Care. She enjoys including her patients in the decision-making process regarding their care to help them reach and maintain their health goals. In her free time, Jennifer enjoys doing volunteer work at the American Heart Association.

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This article is intended for informational purposes only and should not be considered medical advice. Consult a healthcare professional or call a doctor in the case of a medical emergency.

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