A sudden death is a dramatic and/or spontaneous death that is unexpected. It is most commonly due to a dangerous disturbance of the heart’s rhythm caused by a heart condition. A coroner’s post-mortem can exclude most non-heart related causes of sudden death and also diagnose the actual cause if clear abnormalities of the heart’s structure can be detected. There are more subtle forms of heart disease that can cause sudden death but require an expert heart pathologist to examine the heart in order to identify these conditions correctly.
After such an examination there are still around 5-10% of cases occurring amongst children and young people where no definite cause of death can be found. This has been called the Sudden Arrhythmic Death Syndrome or Sudden Adult Death Syndrome (SADS). I collaborated in research undertaken by St George’s and the Brompton Hospitals, London, which suggested that there are up to 500 SADS victims every year in the UK.
When families of SADS victims underwent simple standard heart tests as part of my own research at St George’s Hospital, heart conditions were detected in up to half of families. These conditions were genetic and therefore those relatives found to be carriers were also at potential risk of sudden death. This also therefore explained the cause of the SADS victim’s death. The most commonly identified condition was the long QT syndrome, a genetic abnormality of the electrical function of the heart predisposing it to dangerous and life-threatening rhythm disturbances without causing any abnormalities of the heart’s structure.
This means that whilst the long QT syndrome cannot be detected by a conventional post-mortem it can be detected in life by simple heart tests such as the electrocardiogram (ECG), 24 hour tape monitor and exercise treadmill test. Another more advanced method for detection of the long QT syndrome is to identify the responsible genetic abnormality (known as a mutation) either from blood samples from live relatives who carry the condition or samples of tissue retained from the victim’s post-mortem. This can be successful in half of long QT syndrome families and is known as genetic testing or mutation analysis.
Once a relative has been diagnosed as carrying the long QT syndrome their need for medical treatment must be assessed. Some will never suffer symptoms while others will experience blackouts and/or be at risk of sudden death. There are successful treatments available for the prevention of sudden death but very basic precautions are also helpful even in those who have no symptoms and are at low risk. These include the avoidance of medications that can increase the risk of rhythm disturbances in long QT carriers.
Lisa Browne died suddenly in her bed probably after her alarm went off, waking her suddenly. A post-mortem was unable to explain the cause of her death and her parents Doreen and Terry Harley came to St George’s Hospital, London, in 1999 where I evaluated them. There had been no other unexplained or sudden deaths in the family’s history to otherwise suggest genetic heart disease. Terry’s tests showed him to be a carrier of the long QT syndrome even though he had suffered no symptoms. It was therefore highly likely that he had unknowingly passed on the condition to his daughter Lisa.
Their surviving daughter, Rachel Willn, had suffered blackouts when awoken or disturbed suddenly. She was seen as a matter of urgency and her assessment also detected the long QT syndrome. Both received medication initially but Rachel required further treatment with an implantable defibrillator, which has potentially protected her from a life threatening rhythm disturbance at least once. Blood samples were taken from Terry and Rachel and an abnormality of the long QT syndrome genes was detected: a mutation of the LQT2 genetic subtype. This was also then identified in tissue samples retained from Lisa’s post-mortem further supporting this mutation as the cause of the long QT syndrome in her family and the cause of her death.
Of interest was that sudden death and blackouts in the LQT2 subtype are commonly triggered by sudden and unexpected events such as being woken from sleep by an alarm or doorbell. This was the case for Lisa and Rachel further reinforcing the diagnosis. Rachel has also received genetic counseling to assist her with her children’s management. Another point of interest is that Lisa had received dothiepin in the past. This is a drug that can increase the risk of blackouts and sudden death in long QT syndrome carriers at the time it is being taken and should be avoided.
In summary sudden and unexplained deaths (SADS) do occur and it is important that they are recognized by pathologists and coroners as they indicate the likely presence of genetic heart disease such as the long QT syndrome. This means that other relatives are potentially at risk of sudden death and must be assessed by appropriately qualified specialists as there are life style adjustments and medical treatments available that are known to reduce this risk successfully.
There is also a role for genetic testing and the retention of suitable samples from post-mortems is strongly advised to assist this process. This is also advisable as expert pathologists will be needed to assess the heart properly and completely for the presence of any conditions affecting the heart’s structure that may have caused the sudden death. This advice has been laid out in the recent Chapter 8 of the National Service Framework for Coronary Heart Disease: Arrhythmias and Sudden Cardiac Death