Signs and Symptoms of Sudden Cardiac Arrest

How to Tell if Someone Needs CPR

Sudden cardiac arrest is a serious and life-threatening medical emergency characterized by a sudden loss of consciousness, breathing, and pulse. This may be preceded by dizziness, shortness of breath, a racing heartbeat, or abnormal breathing, though some experience no warnings at all.

The symptoms of cardiac arrest come on suddenly and must be treated with cardiopulmonary resuscitation (CPR) and a defibrillator immediately. Any delay in care increases one's risk of death.

 Man resuscitating another man lying in the road
Jaromir Chalabala / EyeEm / Getty Images

According to a report from the American Heart Association, more than 356,000 out-of-hospital cardiac arrests occur in the United States each year. Nearly 90% of them are fatal.

Preceding Symptoms

Some people who experience cardiac arrest have some sense that something is wrong ahead of time.

Cardiac arrest may be preceded by warning symptoms, such as:

  • Difficulty breathing or shortness of breath
  • Chest pain
  • Nausea and/or vomiting
  • Irregular or racing heartbeat (arrhythmia)
  • Lightheadedness and dizziness
  • Passing out, fainting, or losing consciousness

These symptoms, of course, can be confused with those of several other conditions. Consequently, people often do not realize that there is a problem until the actual cardiac arrest event itself is occurring.

Classic Symptoms

Depending on the cause, cardiac arrest can mimic other conditions.

There are three signs that, when present together, can help you distinguish a cardiac arrest from another emergency. When in doubt, seek emergency medical attention.

Early recognition of cardiac arrest symptoms, along with a fast, appropriate response, can significantly increase one's chances of survival.

Sudden Loss of Consciousness

The stoppage of blood flow to the brain deprives the brain of the oxygen and sugars it needs to function, resulting in the loss of consciousness (syncope). This will occur within seconds of the heart stopping.

Unlike other forms of syncope, in which a person may be affected suddenly or intermittently, loss of consciousness with cardiac arrest will persist until heart function and circulation are restored.

Stoppage of Breathing

At the onset of cardiac arrest, there will often be agonizing gasping motions, labored breathing, and sometimes gurgling, moaning, or grunting.

This is known as agonal respiration, and it is present in 40% to 60% of cardiac arrest cases.

Agonal respiration is not actually breathing, per se, but rather a reflex of the brainstem as it is confronted with a cataclysmic breakdown of heart function.

Typically, this lasts for just a few minutes before a person collapses.

Unless heart function and respiration are restored within minutes, permanent brain damage will occur.

Absence of a Pulse

The absence of a pulse is the central sign of cardiac arrest. Unfortunately, this is the symptom often missed by lay rescuers who don't know how to find a pulse.

Don't waste time looking for a pulse if the person has already collapsed and stopped breathing. Even professional rescuers are being asked to spend fewer than 10 seconds checking for pulse.

Instead, you should initiate CPR and defibrillation immediately.

If an adult has stopped breathing, call 911 and start CPR chest compressions at a rate of 100 to 120 beats per minute. Even if it turns out not to be cardiac arrest, CPR will not harm the individual.

Cardiac Arrest In Children

Each year, at least 20,000 infants and children go into cardiac arrest in the United States.

The American Heart Association (AHA) emphasizes the importance of administering CPR as soon as you recognize an infant or child is not breathing. Again, you should not delay CPR to check for a pulse.

Whereas heart disease is the leading cause of cardiac arrest in adults, children are more likely to go into cardiac arrest due to respiratory failure or asphyxia (oxygen deprivation). Possible causes include respiratory infection, drowning, or drug overdose.

Symptoms of impending cardiac arrest in children can begin minutes to hours before the cardiac arrest event.

Some children may be asymptomatic. Others may have stomach pain, shortness of breath, dizziness, nausea, headache, or pain in their back or neck.

According to the AHA, adequate ventilation is essential when the cause of cardiac arrest is respiratory failure.

Thus, infants and children receiving CPR should be given 20 to 30 breaths and 100 to 120 chest compressions per minute, for a ratio of two breaths per every 30 chest compressions.

Outcomes After Cardiac Arrest

Early CPR with defibrillation is the only way to reverse cardiac arrest. Speed is of the essence if a person is to survive.

For every minute that passes without defibrillation, the chance of survival decreases by anywhere from 7% to 10%. If emergency services arrive and administer defibrillation, survival rates are as high as 49%.

Unfortunately, the more time that passes between the onset of cardiac arrest and treatment, the more likely it is for the cardiac arrest to lead to death.

A Word From Verywell

If you encounter a person who has collapsed and is no longer breathing, act fast and recruit others around you to help.

Cardiac arrest won't suddenly reverse itself and requires immediate hands-on intervention. Call 911 right away and, if you're able, perform CPR until help arrives.

9 Sources
Verywell Health 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. Panchal AR, Bartos JA, Cabañas JG, et al. Part 3: Adult basic and advanced life support: 2020 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation. 2020;142(16):s366-s468. doi:10.1161/CIR.0000000000000916

  2. National Heart, Lung, and Blood Institute. Sudden cardiac arrest.

  3. Benjamin E, Virani S, Callaway C, et al. Heart disease and stroke statistics—2018 update: A report from the American Heart Association. Circulation. 2018;137(12):e67-e-492. doi:10.1161/CIR.0000000000000558

  4. Shen WK, Sheldon R, Benditt D, et al. 2017 ACC/AHA/HRS guideline the evaluation and management of patients with syncope: A report of the American Heart Association Task Force on clinical practice guidelines and the Heart Rhythm Society. Circulation. 2017;136(5):e60-e122. doi:10.1161/CIR.0000000000000499

  5. Chan J, Rea T, Gollakota S, Sunshine JE. Contactless cardiac arrest detection using smart devices. NPJ Digital Medicine. 2019;2(1):1-8. doi:10.1038/s41746-019-0128-7

  6. Welbourn C, Efstathiou N. How does the length of cardiopulmonary resuscitation affect brain damage in patients surviving cardiac arrest? A systematic review. Scand J Trauma Resusc Emerg Med. 2018;26(1):77. doi:10.1186/s13049-018-0476-3

  7. Merchant R, Topjian A, Panchal A, et al. Part 1: Executive summary: 2020 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation. 2020;142(suppl 2):s337–s357. doi:10.1161/CIR.0000000000000918

  8. Atkins D. Cardiac arrest in children and young adults. Circulation. 2012;126(11):1325-1327. doi:10.1161/CIRCULATIONAHA.112.129148

  9. Winkel BG, Risgaard B, Sadjadieh G, Bundgaard H, Haunsø S, Tfelt-Hansen J. Sudden cardiac death in children (1-18 years): symptoms and causes of death in a nationwide setting. European Heart Journal. 2014;35(13):868-875. doi:10.1093/eurheartj/eht509

Additional Reading

By Rod Brouhard, EMT-P
Rod Brouhard is an emergency medical technician paramedic (EMT-P), journalist, educator, and advocate for emergency medical service providers and patients.