SADS
SUDDEN ARRHYTHMIC
DEATH SYNDROME
Sudden arrhythmic death syndrome, or SADS, is when someone passes away suddenly
after a cardiac arrest with seemingly no obvious reason for it.
We are one of many organisations who are passionate about spreading awareness on SADS
and supporting all research into early diagnosis and preventative measures.
WHAT IS SADS?
Sudden Arrhythmic Death Syndrome (SADS) is when someone dies suddenly and unexpectedly from a cardiac arrest, but no clear cause can be found, even after a post-mortem.
A cardiac arrest happens when the heart suddenly stops pumping blood around the body. This stops breathing and cuts off oxygen to the brain, leading to death if not treated immediately.
Normally, the heart’s rhythm is controlled by electrical signals. When these signals malfunction, they can cause an abnormal heart rhythm—known as an arrhythmia. Some arrhythmias are life-threatening and can lead to cardiac arrest if not treated.
After death, the heart’s electrical system no longer works, and the structure of the heart may look normal. This makes it hard for doctors to see what went wrong. If no other cause is found, the death may be diagnosed as SADS.
SADS affects around 500 people in the UK each year, often young and otherwise healthy individuals.
WHAT CAUSES SADS?
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SADS usually happens when a dangerously abnormal heart rhythm goes untreated and leads to a cardiac arrest. These abnormal heart rhythms are called arrhythmias. Not all of them are dangerous. An arrhythmia usually causes the heart to beat too fast, too slow or irregularly. It's usually caused by a heart condition that affects the heart’s electrical system.
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Sometimes, the heart condition that causes the arrhythmia can be inherited. Inherited heart conditions are often the cause of SADS if the person who has it doesn't know they do.
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These conditions include:
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Long QT Syndrome (LQTS)
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Brugada Syndrome
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Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT)
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Progressive Cardiac Conduction Defect (PCCD).
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There are a few conditions that can cause SADS because of very subtle changes to the heart. SADS may still be diagnosed because the structural changes are too small to be seen when the heart is examined after death.
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These conditions include:
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Hypertrophic Cardiomyopathy (HCM)
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Dilated Cardiomyopathy (DCM)
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Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC)
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Thanks to research, we now know that these conditions are caused by changes (or mutations) in one or more of our genes. We can sometimes discover these changes with genetic testing for family members, known as cascade testing. In some cases, this is the only way of telling if someone has an inherited heart condition or if they are at risk of developing one.
WARNING SIGNS
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Family history of unexpected, unexplained sudden death under age 40.
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Fainting or seizure during exercise, excitement or startle.
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Consistent or unusual chest pain and/or shortness of breath during exercise.
How SADS Can be inherited?
SADS (Sudden Arrhythmic Death Syndrome) conditions are often inherited, meaning they can be passed down from a parent to their children.
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If a parent has an inherited SADS condition, each child has a 50% chance of inheriting it.
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These conditions affect the electrical system of the heart, causing it to beat in an abnormal rhythm (arrhythmia).
Who is at risk?
It's estimated that over half of the 4,000 SADS-related deaths each year in children, teens, and young adults had one or both of these warning signs:
Family history
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A known SADS diagnosis in the family
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Or a sudden, unexplained death in a relative (often undiagnosed and untreated)
Fainting (syncope)
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Especially during exercise, emotional stress, or sudden fright
These signs can be crucial clues to detecting a heart rhythm problem early—before it becomes life-threatening.
SADS DIAGNOSIS
Receiving a SADS diagnosis can feel overwhelming — but you're not alone, and there is hope.
Whether you're just beginning to suspect a SADS condition, or you've already been diagnosed, we’re here to provide the support and information you need.
With the right diagnosis and appropriate treatment, people with SADS conditions can go on to live healthy, full, and active lives and truly thrive.
Explore the resources here to help you understand your condition, manage it well, and feel confident about the future.
We would encourage you to reach out to your doctor, and they will be able to put you in touch with a localised specialist.
Or, reach out to us if you are unsure, and we will look to steer you in the best direction to give you peace of mind.