SADS - Sudden Arrhythmia Death Syndrome

What is SADS?

In the context of cardiology, the term SADS refers to Sudden Arrhythmia Death Syndrome. However, the media sometimes refers to SADS as 'Sudden Adult Death Syndrome'; or use SADS for referring to the more general notion of a sudden death of an apparently fit and healthy young person.

In about 1 in every 20 cases of sudden cardiac death and up to 1 in 5 young sudden cardiac deaths, no definite cause of death can be found, even after drugs have been excluded and an expert cardiac pathologist has examined the heart for structural abnormalities.  In such cases, the death will be attributed to sudden arrhythmia death syndrome (SADS).

It is thought that cot death - sudden infant death syndrome, or SIDS - may be partly due to the same causes as SADS.

The conditions responsible for SADS cause a cardiac arrest by bringing on a ventricular arrhythmia, even though the person has no disease affecting the structure of the heart.

The cardiac channelopathies / arrhythmia syndromes are a group of relatively rare diseases that affect the electrical functioning of the heart without affecting the heart's structure.  They are often the cause of a SADS death.  There are several different types of ion channelopathies, including:

• Long QT syndrome
• Brugada syndrome
• PVT (catecholaminergic polymorphic ventricular tachycardia)
• PCCD (progressive cardiac conduction defect)
• Short QT syndrome
• Early repolarisation syndrome
• Sodium channel disease
• Familial atrial fibrillation

Less frequently, SADS can be caused by other cardiac abnormalities, such as extra electrical pathways or even subtle heart muscle disease (cardiomyopathies).