What Is Cardiac Arrest?

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Cardiac arrest happens when your heart abruptly stops effectively pumping blood out to the rest of the body, resulting in loss of a pulse and oftentimes death. The American Heart Association estimates that in the U.S., cardiac arrest is responsible for over 430,000 deaths per year. Cardiac arrest is often caused by underlying health conditions, such as heart disease, electrolyte abnormalities, or pulmonary embolism. In some cases, you can have a cardiac arrest due to drowning, blunt force trauma, and drug overdose.

Medical Emergency

If you witness someone collapse or experience a cardiac arrest, it is absolutely essential to call 911 for help and start immediate cardiopulmonary resuscitation (CPR). This is the only hope for survival for those with cardiac arrest.


Types of Cardiac Arrest

There are different types of cardiac arrest, which include:

  • Cardiac arrest: The heart abruptly stops working, resulting in a loss of blood flow and circulation
  • Sudden cardiac arrest: A cardiac arrest that occurs unexpectedly
  • Sudden cardiac death: Occurs when a cardiac arrest results in death
  • Aborted sudden cardiac death: Happens when CPR and medical intervention effectively prevents death caused by a cardiac arrest

Signs and Symptoms

If you witness someone who suddenly collapses, is gasping, or is unable to breathe, err on the side of caution and suspect that they are undergoing a cardiac arrest. At this time, it's paramount to begin CPR. This could be the difference between life and death. It is estimated that immediate CPR can double or triple the chances of survival.

Be on the lookout for the following signs of cardiac arrest:

  • Sudden collapse
  • Loss of consciousness
  • Inability to wake up even after shaking them or shouting
  • Gasping for air or lack of breathing
  • Not having a pulse


Cardiac arrest occurs when the heart is suddenly unable to deliver blood to the body. Your organs and tissues require a constant supply of oxygen from the blood to survive. The brain is especially vulnerable to periods of low oxygen—a complication known as ischemia. Lack of blood flow to the brain, called cerebral ischemia, leads to collapse and loss of consciousness within seconds during a cardiac arrest.

The underlying medical conditions that can lead to cardiac arrest include:

  • Heart conditions: Includes heart attack, cardiac tamponade, cardiomyopathy, congenital heart disease, and myocarditis
  • Pulmonary embolism: A blood clot in the lungs
  • Electrolyte abnormalities: Conditions such as hyperkalemia, hypokalemia, and hypomagnesemia

You can also experience cardiac arrest due to:


Determining the underlying cause of a cardiac arrest is important so that your healthcare provider can offer the appropriate treatment. During a cardiac arrest or shortly after resuscitation, the following labs, heart studies, and imaging tests can help diagnose or rule out conditions that caused the cardiac arrest to occur:

  • Electrocardiogram (ECG or EKG) to look for signs of irregular heart rhythms and heart attack
  • Lab studies including blood chemistry tests for electrolytes and blood gas studies for blood pH and oxygen levels
  • Chest imaging such as X-ray and computed tomography angiography (CTA) to identify lung problems like a pulmonary embolism or pneumothorax
  • Echocardiogram (a heart ultrasound) to look for cardiac tamponade (fluid around the heart that impairs cardiac output) and structural heart disease
  • Other heart tests such as cardiac catheterization to identify blockages in coronary arteries (your heart's blood vessels) or an electrophysiology study to look for underlying heart rhythm problems


During a cardiac arrest, there is no heartbeat to provide blood flow to the brain and other major organs. Every second counts, so it's essential to recognize cardiac arrest and start immediate cardiopulmonary resuscitation (CPR). CPR involves pressing on the chest to provide blood flow to give someone the best chance at surviving. Without CPR, cardiac arrest is fatal.

Here are brief steps to perform hands-only CPR:

  • Call for help: Call 9-1-1, and if in a public place, request an AED (automatic external defibrillator)
  • Get in position: Ensure the person is lying flat on the ground, kneel beside them, and lock your elbows and keep your arms straight before starting compressions
  • Press hard and fast on the center of the person's chest continuously: The rate of compressions should be between 100 to 120 compressions per minute, with strength enough to depress the chest about 2 inches down
  • Continue CPR: Keep going until medical help arrives

The Purpose of an AED

An AED (automated external defibrillator) is a life-saving machine that is found in many public places. You may notice these boxes hanging on the wall at airports, gyms, shopping malls, or office buildings. An AED includes pads to connect to a person, which can deliver a shock to their chest to restore a normal heart rhythm.

While it might seem intimidating, AEDs are simple to use, and when turned on, they provide audible instructions on what to do. Here is how to use an AED:

  • Expose the person's bare chest
  • Place the pads as instructed by the pictures on the pads
  • If the machine advises delivering a shock, ensure no one is touching the person, and then press the button to deliver a shock

Emergency medical personnel are trained in advanced resuscitation measures, and when they arrive they will lead CPR efforts and transport the person to an emergency department, where they can employ additional treatment measures.

The treatments that emergency healthcare providers can use depend on the underlying cause of the cardiac arrest. These may include medications, medical procedures, and surgery. For example, a common cause of cardiac arrest is a heart attack. Generally, a provider can treat a heart attack-induced cardiac arrest with a procedure called cardiac catheterization, which places a stent in the blocked blood vessels in the heart to restore blood flow.

How to Prevent Cardiac Arrest

In most cases, a cardiac arrest happens suddenly, can't be prevented, and can happen to anyone—including those who don't have an underlying heart condition. Keeping a healthy heart is one way to decrease the risk of cardiovascular disease that can lead to cardiac arrest. This includes lifestyle management and treating underlying conditions. If you may be at risk for heart disease, the following lifestyle habits may help lower your risk of cardiac arrest:

  • Eat a heart-healthy diet that incorporates fruits and vegetables, whole grains, nuts, and legumes
  • Limit intake of salt, processed foods, and trans fats
  • Get moderate physical exercise throughout the week
  • Avoid smoking tobacco
  • Get your cholesterol, blood pressure, and blood sugar levels periodically checked by a healthcare provider, and keep these numbers in a normal range

If you have a family history of cardiac arrest or heart disease, it's a good idea to talk to your healthcare provider to discuss your risks and learn about prevention methods that are right for you. .


Cardiac arrest is fatal without immediate treatment. Even with treatment, survival rates tend to be low. Only 10% of people who have a cardiac arrest outside of a hospital survive. However, up to 60% of people who experience cardiac arrest in a hospital survive. That's why knowing the signs of a cardiac arrest and beginning CPR as quickly as possible is so imperative.

Among those who do survive a cardiac arrest, serious complications can arise due to lack of blood flow during cardiac arrest. These include:

Frequently Asked Questions

  • Can stress cause cardiac arrest?

    While it's fairly rare, sudden emotional stress can lead to cardiac arrest. Stress-induced cardiomyopathy, also known as broken heart syndrome or Takotsubo cardiomyopathy, can result from severe psychosocial or physical stress. This causes the heart muscle to temporarily weaken, which can lead to an irregular heart rhythm and sudden cardiac death.

  • How fast do you pass out after cardiac arrest?

    During cardiac arrest, the heart stops immediately supplying blood to the brain, resulting in loss of consciousness. This can happen in a matter of seconds because the brain is very sensitive to a lack of oxygen. If untreated, cardiac arrest can be fatal within minutes.

  • How long can cardiac arrest last?

    Cardiac arrest can cause death within minutes without medical intervention or CPR. CPR during cardiac arrest can last minutes to over an hour or longer, based on the individual situation and the discretion of the medical providers.

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16 Sources
Health.com uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American Heart Association. CPR facts and stats.

  2. Tsao CW, Aday AW, Almarzooq ZI, et al. Heart disease and stroke statistics-2023 update: A report from the American Heart AssociationCirculation. 2023;147(8):e93-e621. doi:10.1161/CIR.0000000000001123

  3. Podrid PJ. Overview of sudden cardiac arrest and sudden cardiac death. In Post TW. UptoDate. UpToDate; 2023.

  4. National Heart, Lung, and Blood Institute. Cardiac arrest symptoms.

  5. Podrid PJ. Pathophysiology and etiology of sudden cardiac arrest. In Post TW. UptoDate. UpToDate; 2023.

  6. National Heart, Lung, and Blood Institute. Cardiac arrest diagnosis.

  7. American Heart Association. Hands-only CPR.

  8. American Heart Association. What is an automated external defibrillator?

  9. Panchal AR, Bartos JA, Cabañas JG, et al; on behalf of the Adult Basic and Advanced Life Support Writing Group. Part 3: adult basic and advanced life support: 2020 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular CareCirculation. 2020;142(suppl 2):S366–S468. doi: 10.1161/CIR.0000000000000916

  10. American Heart Association. American Heart Association recommendations for physical activity in adults and kids.

  11. Arnett DK, Blumenthal RS, Albert MA, et al. 2019 ACC/AHA guideline on the primary prevention of cardiovascular disease: A report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice GuidelinesCirculation. 2019;140(11):e596-e646. doi:10.1161/CIR.0000000000000678

  12. Amacher SA, Bohren C, Blatter R, et al. Long-term survival after out-of-hospital cardiac arrest: A systematic review and meta-analysisJAMA Cardiol. 2022;7(6):633–643. doi:10.1001/jamacardio.2022.0795

  13. Centers for Disease Control and Prevention. Cardiac arrest infographic.

  14. Gili S, Cammann VL, Schlossbauer SA, et al. Cardiac arrest in takotsubo syndrome: results from the InterTAK RegistryEur Heart J. 2019;40(26):2142-2151. doi:10.1093/eurheartj/ehz170

  15. MedlinePlus. Sudden cardiac arrest.

  16. MedlinePlus. Cerebral hypoxia.

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