Sudden Cardiac Arrest
Genetic Causes
Sometimes individuals are born with a genetic change which impacts the structure or rhythm of their heart. The genetic change may not be noticeable from a person’s appearance or health history. The genetic change may increase the risk of a person suffering a sudden cardiac arrest at some point in their life. Genetic testing can help us identify these changes (see below link for more information) however sometimes even if genetic testing comes back negative we can still be suspicious of a genetic cause.
Structural changes
Conditions which change the structure of the heart (cardiomyopathies) can be picked up through imaging of the heart.
Genetic heart conditions that affect the structure of the heart:
Hypertrophic Cardiomyopathy
(HCM)
The heart muscle becomes thicker
Dilated Cardiomyopathy
(DCM)
The heart enlarges and becomes big and baggy, so it does not pump properly
Arrhythmogenic Cardiomyopathy (ACM)
Causes rhythm problems in the heart and can impact how well the heart works
Rhythm changes
Conditions which change the rhythm of the heart may be identified through tests that can record the electrical system such as electrocardiogram (ECG), exercise tests and holter monitors. Electrical signals of the heart beat are invisible, so they cannot be seen on heart image tests.
Sometimes when it is not clear what has caused a cardiac arrest, genetic testing can help find the reason. If no cause of cardiac arrest is identified on genetic testing, a genetic heart rhythm can still be suspected.
Long QT Syndrome
A rhythm problem of the heart, where the heart takes too long to relax between beats
Brugada Syndrome
A rhythm problem of the heart that causes a dangerous, irregular heartbeat
Catecholaminergic polymorphic ventricular tachycardia (CPVT)
A rhythm problem of the heart which can be made worse by exercise or an adrenaline hit e.g. riding a rollercoaster
Other genetic conditions
There can be inherited cardiac conditions that impact the heart directly. However some genetic conditions can also affect other parts of the body as well as the heart
Aoropathy/Marfan Syndrome
These diseases affect the parts of your body that connect other parts together. The diseases can cause a tear in the body’s main blood vessel, the aorta. Find out more.
Familial hypercholesterolaemia (FH)
A genetic syndrome which can cause high cholesterol leading to a higher chance of coronary artery disease.
Hereditary cardiac transthyretin amyloidosis (ATTR)
A condition that leads to abnormal proteins building up in different parts of the body. Abnormal proteins can build up in the heart muscle. This may affect the ability for the heart muscle to pump, and may increase the chance of a dangerous irregular heartbeat. The cause of most cases of ATTR is not genetic.
Clinical screening of first degree relatives
If a genetic cause of a sudden cardiac arrest is identified or suspected, then it is important that first degree relatives (parents, siblings, children) have clinical screening with a cardiologist. You will need to see your GP to arrange a referral to a cardiologist.