Genetic screening should be routine in sudden death post-mortems: experts

POST-mortems following sudden unexplained death should include routine screening for genetic mutations such as long QT syndrome to improve diagnosis and prevention of sudden death among first-degree relatives, experts say.

Professor Chris Semsarian, a molecular cardiologist at the Royal Prince Alfred Hospital and the Centenary Institute in Sydney, told the Cardiac Society of Australia and New Zealand Annual Scientific Meeting in Sydney last weekend that post-mortem DNA testing was especially warranted in deaths under the age of 35.

Professor Semsarian said genetic screening of family survivors identified an average of 8.9 family members at risk of sudden death in each case.

“We believe it’s an important diagnosis of the cause of death in anywhere up to 30% to 40% of families and the genetic diagnosis can be used in conjunction with clinical screening,” he said.

Family members with gene mutations such as long QT syndrome could avoid triggers like competitive sports, use beta-blockers or in severe cases receive an implantable defibrillator, he said.

Dr Jon Skinner, a paediatric cardiologist at Starship Children’s Hospital in Auckland, NZ, agreed post-mortem genetic screening in unexplained sudden deaths was viable. However, he warned genetic testing for long QT syndrome was imperfect.

“We don’t have ideal tests for sudden cardiac syndromes, there is potential for much social and psychological harm,” said Dr Skinner, a member of New Zealand’s Cardiac Inherited Diseases Group.

He said half of all long QT syndrome carriers would remain asymptomatic, and long QT syndrome testing was not very helpful for risk stratification.

“In terms of risk stratification in that age it’s the QT, and the history and the gender that matter, not the gene type,” he said.

Based on the same research, an analysis of the effectiveness of beta-blockers found they reduced the rate of sudden death by 53% in children aged 1 to 12 years and by 60% in adults.

“It’s not very good is it… reducing your chance of death by half, and this is the mainstay of treatment for long QT syndrome, you’re half as likely to die if you take this as you were before,” he said.