Heart Attack vs. Cardiac Arrest: Signs and First Aid

Heart attack and cardiac arrest are two terms that are often confused.  They are both problems with the heart that require emergency medical attention. However, their causes, symptoms, and treatments are different. Knowing the difference can save someone’s life.


What is a Heart Attack?

A heart attack, or myocardial infarction, is a circulation problem.

Myocardial – relating to the heart’s muscle tissue

Infarction – the injury or death of tissue caused by inadequate blood supply

Over a person’s lifetime, calcium, protein, cellular waste, and fatty substances like cholesterol form plaques on the walls of arteries.   A plaque deposit can rupture, causing a catastrophic blood clot.  If this happens in the coronary artery, which supplies oxygenated blood to the heart, the heart starts to die.



Symptoms can vary but two out of three people will have chest pain[1] The pain can range from severe to mild discomfort.  People describe the sensation as pressure, squeezing, pounding or fullness in the chest.[2]  The feeling can radiate across the upper body, to the arms, shoulders, back, neck, jaw, or upper stomach.  Some people confuse it for indigestion or heartburn.  Others confuse it for angina, which is a form of chest pain, but angina symptoms only last for a few minutes. Heart-attack symptoms persist for more than a few minutes, get worse, or go away and come back.

The second most common symptom is shortness of breath.  Others include sudden sweating, nausea or vomiting, unusual fatigue or fainting.  The pulse can be rapid or irregular.  Skin can look pale or bluish around the lips, hands, or feet.

If the clot only partially blocks the artery, symptoms can build up over weeks, days, or hours before the heart-attack.  Severe blockage can cause a sudden onset of symptoms.  One study found that less severe heart attacks can actually be deadlier, because people typically take longer to seek medical attention.[3]


What to Do:

If you suspect someone is having these symptoms, immediately call 9-1-1.  Even if their symptoms are in the mild range, do not hesitate to call an ambulance. Without oxygen, muscle cells begin to die in 15-30 minutes.  This causes a cascade of irreversible damage to the heart muscle’s structures and functions, which can cause the heart to stop beating (cardiac arrest).  EMS technicians can administer life-saving medicines and treatments as soon as they arrive.  One study found that if paramedics administer a glucose/insulin/potassium solution, they can reduce the risk of cardiac arrest and death by 50 percent.[4]  While you wait for help to arrive, give the person crushed aspirin, if they don’t have an allergy.  Aspirin can limit damage to the heart and save their life.


What is a Cardiac Arrest?

Cardiac arrest is a term for when the heart completely stops working.

Cardiac – related to the heart

Arrest – to stop


Cardiac arrest can be caused by virtually any heart condition; a heart-attack is just one of them.  Whereas a heart-attack is a circulatory problem, cardiac arrest is an electrical malfunction that causes the heart to stop pumping blood to the brain and vital organs.  Heart-attacks usually do not stop the heart from beating, but someone can go into cardiac arrest after having a heart-attack or while recovering from one, especially during the first six months.

The most common mechanism of cardiac arrest is ventricular fibrillation, an irregular rhythm where scrambled electrical signals cause the ventricles (lower chambers) to twitch instead of pump.[5]  The tissue damage caused by a heart-attack is the most common cause of ventricular fibrillation,[6] which is why the two are commonly confused.  Other abnormal rhythms like ventricular tachycardia (fast heartbeat), and bradyarrhythmias (slow heartbeat) can also cause cardiac arrest.



Unlike a heart-attack, a cardiac arrest has unmistakable, drastic effects. Within seconds, the person loses consciousness and becomes unresponsive. They will have abnormal or no breathing, and no pulse.  It is synonymous with clinical death.[7]  Some people experience nausea or vomiting, heart palpitations, or show other symptoms similar to a heart-attack—sometimes weeks, sometimes just moments before the cardiac arrest.  However, more than half of all cases lack these warning signs altogether.[8]  Without emergency treatment, the person will die within minutes. You need to act fast.  The only way to save them is by using a combination of CPR (cardiopulmonary resuscitation) and an AED (automated external defibrillator).


What to Do: CPR + AED

CPR circulates blood and oxygen through the body, and most importantly to the brain.  If given properly and immediately, CPR can keep the person alive until their heart is restarted.  Over 350,000 cardiac arrests happen outside of the hospital each year in the U.S.. Over 90% of these people die. [These mostly occur at home (70%), followed by public settings (18.8%), and nursing homes (11.2%)].  CPR can double or triple their chances of survival, but over 70% of Americans cannot perform the procedure effectively.[9]

CPR alone will not rescue the person.  In order to reverse cardiac arrest, you need to use an AED device, which sends an electrical shock that resets the heart’s rhythm.  AEDs work for the most common arrhythmias: ventricular fibrillation and ventricular tachycardia.  AEDs are found in public spaces like office buildings, schools, malls, event centers, planes, and nursing homes. Emergency responders like EMTs, police officers, and firefighters carry them as well.

Whereas manual defibrillators are designed for trained professionals, automated defibrillators can be used by just about anyone.  AEDs provide step-by-step voice instructions as soon as they are turned on.  Once the electrode pads are placed on the chest, the machine automatically scans for the heartbeat.  The AED is programmed to trigger only if it detects a shockable arrhythmia.  This safeguards against shocking a person who has a non-shockable arrhythmia or is not having a cardiac arrest at all. Some advanced AEDs can calibrate the shock attributes by measuring the resistance level of the person’s body or by being switched to a child/infant mode.  Most devices can also filter out background electrical noise, such as the signals from a pacemaker.


Training and First Aid During the COVID Pandemic:

Effective training can make the difference between life and death when using CPR, and even AEDs.  Although AEDs provide voice and visual instructions, practice using the device could help a person’s confidence and competence in an emergency situation where every second counts.  If cardiac arrest happens to a coworker, knowing where the AEDs are located in the workplace could save their life. Training also provides one other key element: awareness of where the AED is located within their facility – many cardiac deaths occur with responders not knowing that an AED is close-by.

As people gradually return to the offices after over a year and a half of working from home, many will have forgotten their medical emergency training.  Conditioning to social distancing practices and a heightened awareness of infectious diseases can inhibit a coworker or bystander from helping, which requires close quarters and physical contact. One study found that more people died from cardiac arrest during the pandemic because bystanders were less likely to perform CPR or use an AED and EMS response times were slower.[10] COVID’s strain on first responders has made training the community more critical than ever.

In response to the COVID pandemic, OSHA now recognizes online courses for CPR and AED certification.  Virtual CPR courses use video conferencing and personal manikins to train employees remotely, allowing training providers to meet the high demand for recertification while maintaining social distancing and hygienic standards. These courses not only make sure that employees protect themselves from COVID during the training itself, they teach them how to avoid getting infected while they are saving someone.


[1] Cedars-Sinai Staff. “Heart-Attack, Cardiac Arrest, Heart-Failure–What’s the Difference?”. Cedars-Sinai Blog. 2017

[2] National Health Blood and Lung Institute (NHBLI). Heart Attack.

[3] Mirzaei S, Steffen A, Vuckovic K, et al. The association between symptom onset characteristics and prehospital delay in women and men with acute coronary syndrome. Eur J Cardiovasc Nurs. 2019. doi:10.1177/1474515119871734.

[4] Elkind, Mitchell S.V., et. al. Time Delay, Infarct Size, and Microvascular Obstruction After Primary Percutaneous Coronary Intervention for ST-Segment–Elevation Myocardial Infarction. ​​Cardiovascular Interventions. 2021. doi:10.1161/CIRCINTERVENTIONS.120.009879

[5] National Heart, Lung, and Blood Institute. “What Causes Sudden Cardiac Arrest?”. NHLBI. June 22, 2016. Archived from the original on 28 July 2016. Retrieved 16 August 2016.

[6] Johns Hopkins Medicine. Ventricular Fibrillation. Johns Hopkins University. Accessed 28 Oct, 2021.

[7] Ecc Committee, Subcommittees Task Forces of the American Heart Association (December 2005). “2005 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care”. Circulation. 112 (24 Suppl): IV1-203. doi:10.1161/CIRCULATIONAHA.105.166550. PMID 16314375.

[8] Cleveland Clinic Health Library. Sudden Cardiac Death (Sudden Cardiac Arrest). Cleveland Clinic. 2019.

[9] American Heart Association. CPR Facts and Stats. https://cpr.heart.org/en/resources/cpr-facts-and-stats

[10] Uy-Evenado, Audrey, et. al. Out-of-Hospital Cardiac Arrest Response and Outcomes During the COVID-19 Pandemic. JACC Clin Electrophysiol. 2021.7(1): 6–11 doi: 10.1016/j.jacep.2020.08.010


Brandon Diaz

Brandon Diaz

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