Warning Signs of SCA & Heart Attack

Warning signs of heart attack senior woman

Heart disease does not always affect those in a high-risk category. While heart attack and stroke can usually be caused by circumstances where we have some control, sudden cardiac arrest (SCA) can impact anyone, at any time, anywhere.

By increasing our understanding of the differences between heart attack and SCA, we can greatly improve our ability to help save lives. The most important part in any heart-related event is being able to recognize the warning signs of both SCA and heart attacks and act accordingly.

What Is Sudden Cardiac Arrest?

The term SCA refers to an electrical malfunction within the cardiac system, causing the heart to suddenly stop beating effectively. When SCA occurs, the victim quickly loses consciousness.  Oxygenated blood is no longer being pumped to the vital organs, such as the brain and heart, which will lead to tissue damage and eventual death.  Abnormal heart rhythms seen in SCA that are treatable with a shock from an AED (automated external defibrillator) are ventricular fibrillation (V-fib/VF) and ventricular tachycardia (V-tach/VT).  SCA survival rates tend to be lower than survival rates of heart attacks. Luckily, with more advanced cardiopulmonary resuscitation (CPR) techniques and excellent AEDs now available, there is a higher rate of survival than ever before.

What are the Risk Factors for SCA?

While SCA remains one of the most non-discriminatory maladies of the heart, we can identify several factors that may increase an individual’s risk of suffering a SCA. These factors include a previous SCA or heart attack, a low ejection fraction (the heart’s ability to pump blood), underlying heart conditions, severe heart failure, changes in electrolytes in the blood, a tendency to faint, hyperthyroidism, electrocution, drug abuse, and a family history of heart disease.  

Warning Signs of Sudden Cardiac Arrest

SCA can be much more elusive than a heart attack. It often happens with no warning, leaving its victims with little chance to seek help before the onset. There are, however, a few symptoms of sudden cardiac arrest which can be indicative of an impending event. These can include dizziness, fatigue, chest pain, fainting, blackouts, weakness, heart palpitations, shortness of breath, and vomiting. These are also symptoms of a heart attack, so they shouldn’t be ignored.

How to Treat SCA

Once SCA is identified, it is imperative to initiate an emergency response system by calling for help, calling for an automated external defibrillators (AED) and activating the AHA Chain of Survival.

By far the most important thing in SCA is to keep blood moving through the circulatory system to avoid brain death until a defibrillator can be used. There is a lot of usable oxygen remaining in the blood, even in the case of ceased respiration, which allows for chest compressions to be effective in delivering this life-saving gas. As such, it is important to contact emergency services immediately, then administer CPR, followed by using a defibrillator, if available, to restore the heart’s normal rhythm. The sufferer can die within just a few minutes if CPR is not administered.

Survival rates for SCA events can be up to 38 percent for those treated with bystander CPR and AED devices prior to EMS assistance arriving. This is a marked difference from the approximately 10 percent for EMS-treated cases. This is why it is so vital for everyone – not just emergency responders – to be able to administer CPR and be able to use AEDs.

With intervention from an AED, it has become easier than ever for anyone – with or without medical training – to potentially save a life. These devices are built to not only deliver a rhythm-restoring shock, but to actually diagnose the problem and determine the best way to proceed. This innovation has put life-saving capabilities into the hands of bystanders, having the highest success rate when combined with CPR.

Warning Signs of a Heart Attack

A heart attack is a malfunctioning of the heart muscle due to a blockage in an artery, preventing that area of the heart fed by said artery from receiving oxygen-enriched blood. This leads to tissue death, and the longer the artery remains blocked, the more damage occurs. Although heart attack symptoms are the same as those of many other conditions, they shouldn’t be ignored under any circumstances. It is important to note there are distinct differences in the symptoms experienced by men and women. However, many are symptoms are shared between genders.

A few of the more common heart attack symptoms include chest pain/discomfort, shortness of breath, upper body pain (arms, back, neck, jaw, shoulders), nausea/vomiting, lightheadedness, sweating, anxiety, and abdominal pain.

How Is a Heart Attack Different from SCA?

The key difference between a heart attack and SCA is in the case of a heart attack, there is a heartbeat present and the victim maintains consciousness. The heart usually continues to beat, albeit in a compromised manner. Heart attacks can be brought on through clogged arteries, thickened heart walls and other causes. Heart attacks and SCA can be linked, but they do not necessarily occur together.

How to Treat a Heart Attack

Similar to SCAs, time is of the essence with heart attacks. If you suspect you or someone in your vicinity is having a heart attack or experiencing heart attack symptoms, seek emergency medical treatment immediately. Call 911 (or your emergency code) and get an estimated time of arrival for the ambulance. When possible, have the sufferer lie down until help arrives. If available, have the person chew an aspirin (unless they’re allergic). Should the victim have a prescription of nitroglycerin, they should take it as prescribed. If the person loses consciousness, begin CPR and attach an AED.  If the AED indicates a shock is needed, commence treatment as instructed.

Through increasing our public understanding of these differences, how to treat an SCA or heart attack, how to utilize CPR, and by placing more AEDs in public places we can successfully reduce the number of lives lost to heart disease. For more resources about sudden cardiac arrest, CPR or AED, see our AED Blog here.


SCA Foundation (2010). Study Shows Bystander Use of AEDs Saves Lives. Retrieved from: https://www.sca-aware.org/sca-news/study-shows-bystander-use-of-aeds-saves-lives-0

Chen, M., Zieve, Ogilvie, I., A.D.A.M. Editorial team (2014) Ventricular tachycardia. Retrieved from: https://www.nlm.nih.gov/medlineplus/ency/article/000187.htm

American Heart Association (2015) Heart Attack or Sudden Cardiac Arrest: How Are They Different? Retrieved from: https://www.heart.org/HEARTORG/Conditions/More/MyHeartandStrokeNews/Heart-Attack-or-Sudden-Cardiac-Arrest-How-Are-They-Different_UCM_440804_Article.jsp

Mayo Clinic (2015) Sudden Cardiac Arrest Symptoms and Causes. Retrieved from: https://www.mayoclinic.org/diseases-conditions/sudden-cardiac-arrest/symptoms-causes/dxc-20164872

Mayo Clinic (2015) Heart attack symptoms: Know what’s a medical emergency. Retrieved from: https://www.mayoclinic.org/diseases-conditions/heart-attack/in-depth/heart-attack-symptoms/art-20047744

American Heart Association (2015) Out-of-hospital Chain of Survival. Retrieved from: https://cpr.heart.org/AHAECC/CPRAndECC/AboutCPRFirstAid/CPRFactsAndStats/UCM_475731_CPR-Chain-of-Survival.jsp

Newman, M. (2014) Sudden Cardiac Arrest: A Healthcare Crisis. Retrieved from: https://www.sca-aware.org/about-sca

Mayo Clinic (2015) Heart attack: First aid. Retrieved from: https://www.mayoclinic.org/first-aid/first-aid-heart-attack/basics/art-20056679

Wikipedia (2016) Ventricular fibrillation. Retrieved from: https://en.wikipedia.org/wiki/Ventricular_fibrillation

S. Joanne Dames - MD, MPH

Updated: 1/15/2019

5 Responses to “Warning Signs of SCA & Heart Attack”

January 04, 2017 at 2:46 pm, Hugh Lee said:

How do you seriously know to call 911 or go to the hospital if you think that you’re having a heart attack?


January 18, 2017 at 10:26 am, AED Superstore said:

If you think you are having a heart attack, time is of the essence, and it is always more prudent to err on the side of caution. Call 911 right away, don’t try to drive yourself to the hospital. Yes, it could be an anxiety attack, or indigestion, or some other malady. However, the only way any of these can be accurately diagnosed is to be seen by a physician. Better to be safe than sorry.


January 04, 2017 at 2:48 pm, Hugh Lee said:

how do you know if you’re getting signs of a heart attack?


January 18, 2017 at 10:22 am, AED Superstore said:

The answer to your question can be found in the article: “A few of the more common heart attack symptoms include chest pain/discomfort, shortness of breath, upper body pain (arms, back, neck, jaw, shoulders), nausea/vomiting, lightheadedness, sweating, anxiety, and abdominal pain.” Also, you can check out this link for more details: https://www.mayoclinic.org/diseases-conditions/heart-attack/in-depth/heart-attack-symptoms/art-20047744


February 03, 2017 at 10:55 pm, Raymond said:

My wife could not breathe and her heart pressure was 172/95. I insisted I call ambulance an she said no. And I was going to call her childre nand she said no. I don’t want this to happen again because I will call emergency ambulance regardless. Could she still be at risk tonight.

I won’t sleep to keep an eye on her


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