The mystery of sudden adult death syndrome – and how to know if you are at risk

Each year about 400 seemingly healthy young Aussies die of sudden cardiac-related causes, with autopsies unable to find a specific reason.

You might have heard the term “sudden adult death syndrome” recently – so what is SADS, and what causes it?

In Australia, such deaths are generally called unexplained cardiac arrest or sudden cardiac death, according to Baker Heart and Diabetes Institute cardiologist and researcher Dr Elizabeth Paratz.

“SADS is a term used mostly overseas, and it stands for sudden arrhythmic death syndrome,” Dr Paratz says.

Sudden arrhythmic death syndrome is an “umbrella term to describe unexpected deaths in young people”, usually under 40, whose cause of death is not known despite an autopsy, according to the Royal Australian College of General Practitioners.

What is SADS?

Sudden cardiac death refers to an abrupt lack of heart activity and is one of the biggest killers of Australians under 50.

It is more likely to impact men, and many people affected are generally regarded as fit and healthy.

The main cause of sudden cardiac death in people under 35 is believed to be a genetic heart condition or heart rhythm disorder.

How common is unexplained death in young people?

Dr Paratz works on Australia’s first registry about unexplained cardiac arrest events.

The registry is currently collecting Victorian data, but is expected to be rolled out Australia-wide.

The registry has found there are around 750 cases per year of people aged under 50 in Victoria suddenly having their heart stop (a cardiac arrest).

Of those, no cause will be found for about 100 deaths even after extensive investigations such as a full autopsy.

“So it’s a big number, and if we think of Victoria as roughly representing a quarter of Australia, that would be about 400 young people each year in Australia having a SADs event or unascertained cardiac arrest,” Dr Paratz says.

“And the majority of those didn’t have warning signs or symptoms, or any history of heart problems.”

Research has found the number of SADS deaths is vastly underestimated.

Dr Paratz says one of the problems is that traditionally a lot of cases have not been recorded, because a lot of people die outside the hospital system.

“Ninety per cent of people don’t even make it to hospital, they’re looked after by ambulance staff or the forensic system,” Dr Paratz says.

“We only see 10 per cent (in the hospital), so it’s just the tip of the iceberg.”

The registry is overcoming this problem by combining ambulance, forensic and hospital data.

How to assess your risk of SADS

The RACGP recommends getting checked if you have a family history of arrhythmogenic disorder, you have had a family member with SADS, or you have experienced episodes of unexplained fainting or seizures during exercise, periods of excitement or when startled.

Younger people who are at risk may have rare conditions, often inherited.

Dr Paratz says it is important everyone knows their family’s cardiovascular history.

“If you’re a first degree relative, so a parent, sibling or child, of someone who has had a sudden cardiac arrest, then you’re more at risk, so we do recommend you see a cardiologist, for screening and cardiac investigations,” Dr Paratz says.

Dr Paratz recommends visiting a specialist if you experience:

  • Chest pains
  • Shortness of breath
  • Dizziness

Written by Bianca Carmona.