NZ research sheds light on unexplained deaths

A 25-year-old woman with a young infant collapses after an unexpected visitor rings the doorbell late one evening. Despite the best efforts of her family and the ambulance staff who arrive only minutes later, the woman can’t be revived. Her husband is left a widower and her child without a mother.

This is the sort of case that is referred to the Cardiac Inherited Disease Group (CIDG), a multidisciplinary team of experts from around New Zealand who look into sudden unexplained death cases.

Around 30 percent of unexplained death in the young (between the ages of one and 35) are due to a previously undiagnosed genetic disorder. If we can identify this disorder, we can also identify family members potentially at risk of the same fate. It is this desire to prevent further unexpected death that motivates members of the CIDG to “Detect, Protect and Enable” undiagnosed members of the community who are at risk of sudden cardiac arrest.

Many families who come through our clinic just want to know why their loved one has died prematurely. Even if they don't find a reason, they want to know everything has been done to try to find the answers they so desperately want. This means a lot of detective work for the clinicians involved. It is not so much a "whodunnit?" as a "why did it happen?" and "how can we prevent it happening again?".

Those tasked with investigation of these tragic events often seek help on how best to do this. This is why the Asia Pacific Heart Rhythm Society and the Heart Rhythm Society (of North America) partnered to produce a paper on how to investigate sudden unexplained deaths.

This paper, which began in May 2019 and was published this month, brought together 28 authors from 13 countries across five continents. It represents the opinion of a wide group of health professionals including cardiologists, paediatricians, genetic counsellors, pathologists, clinical geneticists and patient advocates to provide a framework for the thorough investigation of such cases.

In addition to the patients who do not survive sudden cardiac arrest, we also see survivors who do. They too are searching for answers and, in achieving a diagnosis, can have specific therapy designed to prevent future episodes. They may also have an inherited condition and it is important to try and diagnose this as, like with those with sudden unexplained deaths, other members of their family may have inherited the same condition.

The guidelines produced in the paper cover both genetic counselling and the psychological care of the bereaved and the nearly bereaved, aspects of care that can be pushed aside in the rush to provide answers. These aspects are given priority in our recommendations for best practice along with the considerations that must be applied when counselling our families. For instance, will the potential diagnosis of a cardiac condition by genetic testing threaten future employment prospects? Would a genetic diagnosis affect eligibility for health or life insurance? Will genetic testing reveal "non-paternity"? These delicate discussions all take place within the CIDG clinics before we perform genetic testing.

Although genetic diagnosis is an extremely important tool in sudden unexpected death investigations, our guidelines point to leading with clinical tools, for example using ECGs and ultrasound. By doing this, those at risk of malignant cardiac conditions can be identified, and those not at risk who can therefore be released from continued surveillance. Genetic testing is best done after a clinical diagnosis is made. This is why we take great care to examine sudden cardiac arrest survivors and thoroughly investigate those who die unexpectedly via post-mortem and a search of prior medical records. We also often study first-degree relatives (parents, offspring and siblings) of those that have died suddenly, particularly the parents from whom any inherited disease must have originated.

Investigating sudden unexplained death correctly is an important public health issue due to the impact these losses have on individuals, families, communities and wider society. Work in this area brings up issues regarding CPR training, the availability of defibrillators in the community and ways in which we as a society can minimise its occurrence.

Now, when families are referred to us to gain answers about why their loved one died, we have a framework to investigate thoroughly all possible causes so we can provide accurate diagnoses acquired through clinical and genetic means.

Most of our time as doctors is spent in treating individual patients; within the area of inherited cardiac disease, we treat not only individuals but families and communities. Publication of this paper and the guidelines it contains means we are not only helping the patients in front of us and their families, but people we have never met, in countries we may never visit. It means physicians internationally can strive for best practice to achieve the answers these patients and families so desperately want, and protect yet undiagnosed individuals from sudden death.

This is the power of international collaboration and best practice statements that influence worldwide practice for the better. And in this case, New Zealand has led the way.