Posted by allisong on 02/27/2014

New Zealand and Australian doctors are on the verge of discovering why some young people suddenly fall victim to cardiac death.Chris Semsarian

Preliminary numbers show 460 sudden cardiac deaths have been reported in both countries in the past three years, with 51 of these occurring in New Zealand, Australian cardiologist Chris Semsarian says.

Dr Semsarian, who presented early results of his three-year study at the Royal College of Pathologists of Australasia Pathology Update in Melbourne over the weekend, says gene analysis could confirm the underlying cause of these unexplained deaths.

Final results are expected in the middle of this year, he says.

Sudden cardiac death a silent killer

Sudden cardiac death in young people aged between one and 35 who are considered healthy is "like getting hit by a bolt of lightning", Dr Semsarian told New Zealand Doctor.

What's more, the cause of death in up to 50 per cent of these cases remains unknown, even after an autopsy, he says. The other 50 per cent is attributed to blocked arteries, genetic heart disease or heart rhythm problems.

Dr Semsarian says unexplained deaths could be caused by cardiac arrhythmia.

"When you look at the heart, weigh the heart, look [at it] under the microscope, you can't see the electrical system and check if it was faulty or not," he says.

Study to pave the way for gene therapy

Dr Semsarian says, with the help of University of Auckland paediatric cardiologist Jon Skinner, genes responsible for these electrical cardiac glitches are in the process of being identified.

Confirmation of cause of death through genetic testing (NZ$1623 per sample) can provide closure for the family of the deceased, and could also help prevent sudden cardiac death in other family members genetically predisposed to the fatal event, he says.

These relatives could receive personalised gene therapy to reduce the likelihood of sudden cardiac death occurring.

Dr Semsarian says gene therapy is still its early stages but is expected to gain momentum in the next three to five years.

At the moment, translating genetic code into tangible diagnoses still poses challenges, he says.

Family histories should be traced

Dr Semsarian says sudden deaths in the family, even if they are a few generations back, should trigger other family members to take an ECG and a heart ultrasound.

"Initiating family screening is the simplest and the most proactive thing to do," he says.

There has been some talk that New Zealand and Australia should offer ECG to every 14-year-old, but this is an extreme approach, Dr Semsarian says.

Sudden cardiac death is rare, and screening tests can produce false positives, he says.

For every one life saved, there could be 20 young people who receive unnecessary gene therapy.