Preventing sudden death from heart disease

Sudden unexpected death in young people is always a terrible tragedy. While newspaper articles may write headlines such as “adult cot death mystery”, in fact for many cases the cause can be found and the death could have been prevented.

Inherited heart conditions are usually concealed in outwardly healthy people, often right up until the day they die suddenly and unexpectedly. The vigilant family practitioner can be the one who makes the difference.

Consider three cases:*

1. A 21 year old woman who died suddenly and was found to have hypertrophic cardiomyopathy on autopsy.
2. A 10 year old boy treated for epilepsy who had a near drowning.
3. A 35 year old who was found to have idiopathic dilated cardiomyopathy by his cardiologist.

Errors were made in the management of these cases which have resulted ultimately in loss of life. Some useful lessons may be learned. This article describes what happened, and then what should have happened.

Case 1

A 21 year old woman collapsed and died running for a bus. Hypertrophic cardiomyopathy (HCM) was found on autopsy.  The pathologist recommended family screening to the GP.

The GP knew the woman had an older brother of 24. He sent a referral for an outpatient echocardiogram for him to the cardiology department. The report came back as normal, the GP let him know and no further action was taken.

Five years later the young woman’s mother, aged 54, was found dead in the garden. Autopsy revealed severe HCM. Her husband demanded full investigation of the family. His GP (a different GP) referred them to a clinical genetic service which discovered a history of several young deaths in the extended family, including a 21 year old with a defibrillator for HCM. Genetic testing helped find five further presymptomatic individuals, two of whom ultimately went on to receive intracardiac defibrillators for severe HCM.

Hypertrophic cardiomyopathy (HCM)

HCM is quite common at 1 in 500 people.¹  Like most inherited heart diseases, it is inherited in an autosomal dominant fashion. Thus 50% of first degree relatives carry the at risk gene. Gene carriers have variable clinical expression of the disease, and need to be followed by expert cardiology for life, from childhood. Sudden death is a common first presentation, but can be prevented by the use of intracardiac defibrillators.² Detection of presymptomatic individuals is thus imperative, and depends on thorough screening of family members of anyone identified with the condition, even if they are deceased.

Learning points in this case

Any of the clinicians involved in this story should have made a referral to a genetic service to ensure other family members were traced; the pathologist, the deceased woman’s GP, the cardiologist triaging the echo request, and the cardiologist implanting the defibrillator.

Case 2

A 10 year old boy treated for epilepsy was swimming in a race at school when he suddenly stopped moving. He was limp when he was pulled out but he came round quickly. His seizures were usually related to exercise of some sort.

His GP referred him back to his neurologist who changed his antiepileptic medication. He had no seizures for two years. He collapsed suddenly warming up for a school hockey game, witnessed by his parents. Attempts at resuscitation failed.

The autopsy was uninformative. Death was put down to epilepsy initially (“SUDEP”- sudden unexpected death in epilepsy), until a family friend, a paediatrician, referred the family to an arrhythmia specialist. The mother had a long QT interval on her ECG, and subsequent molecular genetic testing of DNA extracted from the deceased boy’s neonatal screening (Guthrie) card revealed long QT type 1.³

Long QT syndrome (LQTS)

LQTS is the most common of the cardiac ion channelopathies (about 1 in 2000 people).⁴ These are disorders of the cardiac potassium and sodium ion channels regulating the cardiac action potential. Others include Brugada syndrome and CPVT (catecholaminergic polymorphic ventricular tachycardia). All are autosomal dominant and cause sudden death in otherwise healthy people who have hearts which appear normal. A family history of young sudden death is common.

In LQTS death can be prevented by beta blockers and avoidance of some medications (www.qtdrugs.org).  There are two common types. LQTS type 1 is the most common; usually worst in boys, and collapse while swimming or during or after exercise is typical.⁵  LQTS type 2 mostly affects women, and death during sleep or after a sudden startle is typical; “nocturnal seizures” may be present.⁶

Learning points in this case

LQTS, CPVT and Brugada are commonly mistaken for epilepsy in non-fatal attacks, since during an attack of rapid ventricular tachycardia there is zero cardiac output, and hypoxic seizures can occur.⁷

Once a misdiagnosis of epilepsy is made, it tends to stick for many years.⁸ The neurologist and the GP had several opportunities to revise this diagnosis prior to his death.  The clinical history is absolutely classical for LQTS type 1.^9,10 An ECG is an easy and cheap test and would have been abnormal. An ECG should always be done after the first afebrile seizure when there is no obvious cerebral pathology.

After sudden unexplained death in a young person, the pathologist should have saved DNA and initiated family screening by referral to a cardiac genetic service.^11-13

Case 3

A 31 year old father of three children presented with palpitations and was found to have a dilated cardiomyopathy (DCM) of unknown cause by the investigating cardiologist. The GP assisted in his management over the subsequent ten years, but he did not refer the family for cardiac assessment.

The man’s father then died suddenly aged 59 whilst working on his car. At autopsy, he had severe DCM.

The original patient, now aged 41, had three children who were then referred for cardiological assessment. One has severe DCM, and the other two were normal and are under surveillance.

Dilated cardiomyopathy (DCM)

DCM has many causes. Most cases beyond childhood are secondary to coronary artery disease and alcohol for example. However, when no cause is apparent, familial DCM must be considered, and accounts for about a third of those where no overt cause is found.  Clinical management can be effective, particularly beta blockers and ACE inhibitors, and cardiac re-synchronisation and defibrillator pacemakers can be life-saving.

Learning points in this case

A thorough family history and full cardiac investigation of at least all first degree relatives is mandatory in all cases of “idiopathic” DCM.

*The cases are real but some details have been changed to protect the identity of the families concerned.

Acknowledgements

Article kindly written by Dr Skinner, who is part funded by Cure Kids.

References

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