Postmortem genetic testing of people who have suffered sudden unexplained death (SUD) is a more effective and cost-efficient means of identifying genetic abnormalities that place surviving relatives at risk of fatal heart rhythm disturbances, a new study presented at the American Heart Association's annual meeting in Orlando, US, suggests.

Every year, almost 300,000 people in America suffer sudden cardiac death; fatality occurs within minutes after an abrupt loss of heart function. Of the victims, approximately 25-30 per cent are a result of genetic defects.

The scientists set about comparing the results and costs of postmortem genetic/molecular autopsy testing in 146 sudden unexplained death cases. Reflecting established values, they found that 26.7 per cent had one of two types of genetic mutation known to cause sudden cardiac death.

The researchers conducted further investigation on the 160 relatives of victims who tested positive for mutations; tests included further genetic screening, treadmill stress tests and electrocardiograms.The total cost of this gene-directed screening of relatives was $6.78 million.

The researchers then compared this line of investigation with the currently recommended comprehensive cardiac testing of all relatives of the sudden unexplained death victims, regardless of their mutation status. The cost exceeded $7.7 million.

'If you identify a mutation in a sudden unexplained death victim, you can do a simple genetic test in first-degree relatives to assess their risk and perform a disorder-directed clinical evaluation rather than a full clinical evaluation. If a relative is negative for the causative mutation, they may not need to undergo further clinical evaluation at all, and that saves money', said study co-author David Tester.

A barrier to the implementation of this research at present however is that insurance companies pay for comprehensive cardiac testing for family members, despite the fact that commercial molecular and genetic testing of the deceased relative can provide just as accurate a risk profile and in many cases negate the need for further clinical testing.

The study had its limitations however and needs to be confirmed by further research. 'The cohort we studied was not a population-based collection of SUD cases but instead involved cases that were referred by coroner's/medical examiner's throughout North America so we don't know what the true yield of postmortem genetic testing for autopsy negative SUD is at this time,' said David Tester.