Sudden Cardiac Arrest
Sudden cardiac arrest is an electrical disturbance in the heart that prevents it from beating properly.
Contact a product expertSudden cardiac arrest (SCA) is an electrical disturbance in the heart that prevents it from beating properly. During SCA, the ventricles flutter in a phenomenon known as ventricular fibrillation, making them unable to deliver blood to the body. The heart responds by quivering, rather than beating in a normal fashion. Blood flow to the brain is reduced to the point that the person loses consciousness and collapses. Unless emergency treatment is provided quickly, the victim's chance of survival is low.
Symptoms of sudden cardiac arrest typically arrive without warning and are notably strong. The most common symptoms include:
Sudden cardiac arrest is caused by a change in the heart's electrical activity. SCA often affects those who have experienced previous episodes of cardiac arrest, heart attacks, or heart failure; but it can also strike someone with no history of heart problems. Though extremely rare, a sudden blow to the chest can also cause SCA. The condition, known as commotio cordis, can occur when a hard object strikes the chest (directly over the heart) at a critical time during a heartbeat.
According to the Heart Rhythm Society, sudden cardiac arrest is a leading cause of death in the United States, accounting for an estimated 350,000 deaths each year.
Though sudden cardiac arrest can strike healthy people of any age who are seemingly not at risk, a number of risk factors can contribute to the likelihood of suffering an SCA event. Fortunately, many of these can be mitigated by lifestyle changes.
The most common risk factors include:
Following a sudden cardiac arrest, once a patient is stabilized, a hospital can perform a number of tests to diagnose SCA:
An electrocardiogram (ECG) checks the heart's electrical activity through the use of sensors (called electrodes) placed around the body, typically on the chest. This test measures heart rate and can show important changes in heartbeat that can indicate cardiac arrest.
Heart imaging tests like X-rays, nuclear scans, coronary catheterization, and echocardiograms use sound waves or other means to create images that can show heart damage and reveal blood flow issues.
Blood tests can reveal the presence and levels of proteins and hormones that indicate a sudden cardiac arrest.
Sudden cardiac arrest must be treated immediately. Treatment involves restoring the heart to its normal beating pattern and must begin with:
With quick action, bystanders can help avert tragedy by performing high-quality CPR. The 2025 American Heart Association Guidelines for CPR and ECC identify five requisite components for providing high-quality CPR:
While CPR keeps oxygenated blood flowing to vital organs, only defibrillation can correct certain types of cardiac rhythms. Through the use of an electric shock, defibrillation can get a heart beating normally again. An automated external defibrillator (AED) can provide a lifesaving shock to an SCA victim. And because SCA can happen anywhere, it's critically important that AEDs are widely available and accessible to the public. With an AED, anyone can help save a life.
The Chain of Survival is a series of steps (called "links") that can help more people survive sudden cardiac arrest. If a layperson witnesses SCA, they should follow these six links of the Chain of Survival:
According to the American Heart Association, sudden cardiac arrest kills over 430,000 people a year in the U.S., with over 350,000 of these deaths occurring outside the hospital. Survival rates decrease 7 to 10% for each passing minute after SCA if no CPR is provided. However, with the benefit of high-quality CPR and an AED, an SCA victim's chance of survival can improve dramatically.
While sudden cardiac arrest can strike without warning, numerous ways exist to reduce risk factors that can contribute to SCA:
Regular appointments with your doctor can reveal preliminary signs of risk factors that may contribute to the likelihood of sudden cardiac arrest. By regularly visiting your doctor, you can identify and manage these risks before they become more serious problems.
A healthy lifestyle can mitigate many risk factors that may contribute to the likelihood of sudden cardiac arrest. Risk factors like high-blood pressure and high cholesterol, obesity, poor nutrition, and smoking can be reduced or eliminated through lifestyle changes like increasing physical activity and dietary changes.
Certain genetic disorders and abnormalities can increase someone's risk of sudden cardiac arrest. A doctor may recommend genetic testing to detect these genetic indicators.
For those at severe risk of sudden cardiac arrest, doctors may recommend an implantable cardioverter defibrillator (ICD). This small, battery-powered device is implanted within the chest to continuously monitor a patient's heartbeat and deliver an electric shock when necessary.
Medical attention must be administered as soon as possible after the victim collapses; the chances for survival decrease 7 to 10% for every minute without intervention. Many SCAs occur outside of the hospital, which is why public access AEDs have the potential to help save the lives of countless loved ones struck by cardiac arrest.
First aid for cardiac arrest should include calling 911, performing high-quality chest compressions as part of CPR, and using an automated external defibrillator (AED) if one is available. Check for safety, summon help, and then start chest compressions immediately (100-120 per minute). If a defibrillator is available, follow the AED prompts.
An automated external defibrillator (AED) is a critical device for responders to sudden cardiac arrest (SCA). AEDs can provide vital , lifesaving electric shocks to restart the heart. During an SCA, every minute that passes without defibrillation decreases the chance of survival by approximately 10%. On-site AEDs help bystanders intervene and dramatically increase the odds of survival.
A heart attack happens when blood flow to part of the heart is blocked, potentially leading to damage or death of heart muscle. Sudden cardiac arrest (SCA) is a medical emergency where the heart's electrical system unexpectedly malfunctions, causing it to stop beating properly.
Sudden cardiac arrest (SCA) is a medical emergency where the heart stops beating correctly, causing the person to collapse, lose consciousness, and stop breathing or gasp for air. Without immediate treatment, blood cannot reach the brain and other vital organs — death can occur within minutes.
Sudden Cardiac Arrest: Know the Facts
Chain of Survival
CPR Overview
Defibrillation
Pacing
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