Sudden Cardiac Arrest

Source: MedlinePlus Health Topics, U.S. National Library of Medicine

Last synced 8/6/2026Status: primary verified

What is sudden cardiac arrest (SCA)? Sudden cardiac arrest (SCA) is a condition in which the heart suddenly stops beating. When that happens, blood stops flowing to the brain and other vital organs. If it is not treated, SCA usually causes death within minutes. But quick treatment with a defibrillator may be lifesaving. How is sudden cardiac arrest (SCA) different from a heart attack? A heart attack is different from an SCA. A heart attack happens when blood flow to the heart is blocked. During a heart attack, the heart usually doesn't suddenly stop beating. With an SCA, the heart stops beating. Sometimes an SCA can happen after or during recovery from a heart attack. What causes sudden cardiac arrest (SCA)? Your heart has an electrical system that controls the rate and rhythm of your heartbeat. An SCA can happen when the heart's electrical system is not working right and causes irregular heartbeats. Irregular heartbeats are called arrhythmias . There are different types. They may cause the heart to beat too fast, too slow, or with an irregular rhythm. Some can cause the heart to stop pumping blood to the body; this is the type that causes SCA. Certain diseases and conditions can cause the electrical problems that lead to SCA. They include: Ventricular fibrillation , a type of arrhythmia where the ventricles (the heart's lower chambers) don't beat normally. Instead, they beat very fast and very irregularly. They can't pump blood to the body. This causes most SCAs. Coronary artery disease (CAD) , also called ischemic heart disease. CAD happens when the arteries of the heart cannot deliver enough oxygen-rich blood to the heart. It is often caused by the buildup of plaque , a waxy substance, inside the lining of larger coronary arteries. The plaque blocks some or all of the blood flow to the heart. Some types of physical stress can cause your heart's electrical system to fail, such as Intense physical activity in which your body releases the hormone adrenaline. This ho

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This information is for general education and is not medical advice. Always talk to a licensed U.S. clinician about your situation, medications, or treatment decisions.