Sudden cardiac death in the youngBMJ 1997; 314 doi: https://doi.org/10.1136/bmj.314.7084.843 (Published 22 March 1997) Cite this as: BMJ 1997;314:843
A family history of sudden death needs investigation
- J F Goodwin, Presidenta
The sudden death from cardiac causes in a young, active, and apparently healthy adolescent or young adult is a major catastrophe. Of the several cardiac causes–including congenital heart disease, congenital anomalies of the coronary arteries, Marfan syndrome, and myocarditis–the commonest cause in young sports people is hypertrophic cardiomyopathy.1 In one study 70% of patients with hypertrophic cardiomyopathy who died suddenly did so before the age of 30 years, and 40% died during or after exertion.2 Such deaths are preventable, so why are they not prevented?
The incidence of hypertrophic cardiomyopathy in the United States is about 1 in 500,3 which suggests that there are likely to be at least 100 000 cases in Britain. However, this is an underestimate because many people have mild disease and live for many years unrecognised. For them, the sudden death of an offspring is likely to be the first “symptom.”
Hypertrophic cardiomyopathy is usually, if not always, familial.4 In the familial form, mutations are present in genes coding for sarcomeric contractile proteins. In sporadic hypertrophic cardiomyopathy, de novo mutations occur in the same genes, indicating that the sporadic and familial forms have the same disease process.
Identifying people at risk is vital for effective intervention. Widespread population screening is not appropriate, but individuals with a family history of sudden cardiac death and/or cardiomyopathy must be carefully examined for evidence of disease. The first clue usually comes from the family history, but suspicious symptoms reinforce the need for investigation. Careful clinical examination, electrocardiography, and echocardiography will detect most cases.
In some cases echocardiography is normal but the electrocardiogram is mildly abnormal, perhaps because myocardial disarray can occur in the absence of hypertrophy. A few patients may need more specialised investigations such as effort testing and blood pressure responses to vascular manoeuvres, especially when there are signs that overlap with those of the athletic heart. Factors suggesting a high risk of sudden death are young age, history of aborted sudden death, strong family history of sudden death, syncope, abnormal blood pressure response to effort, and arrhythmias including occult conduction disease.5 People with such risk factors need accurate diagnosis, and Holter monitoring to detect arrhythmias is essential to guide appropriate treatment.
Although there is as yet no cure, there is much that can be done to improve symptoms and prognosis and reduce the risk of sudden death. Advice on lifestyle and drugs such as ß adrenergic blockers and calcium channel blockers can improve symptoms, while amiodarone can improve prognosis by controlling arrhythmias.6 Implantable cardioverter defibrillators may prevent sudden death in patients with intractable arrhythmias, while dual chamber pacemakers may improve symptoms and effort tolerance.7 Surgical treatment, including transplantation, may be useful for a small proportion of cases with special indications.
Two other cardiomyopathies–dilated cardiomyopathy and arrhythmogenic right ventricular dysplasia–are also important causes of sudden death.The incidence of dilated cardiomyopathy in the United States is 3-10 per 10 000, with 20 000 new cases being diagnosed annually.8 It is now known that more than 20% of cases of dilated cardiomyopathy are familial,9 and molecular genetic abnormalities have been found. Pathogenesis remains uncertain, but there is an association with enteroviral infection as well as evidence of autoimmunity, including the presence of disease specific antibodies that recognise cardiac and ß myosin heavy chain and other as yet unidentified antigens.
Early diagnosis has greatly improved the prognosis of dilated cardiomyopathy, as have better understanding of the disease, more sensitive diagnostic tools, better treatments, and greater awareness of the indications for cardiac transplantation and its timing. Four year survival increased from 54% in patients diagnosed during 1978-82 to 83% in those diagnosed during 1988-92.10
The detection of hypertrophic cardiomyopathy, dilated cardiomyopathy, or arrhythmogenic right ventricular dysplasia offers the prospect of treatment that will improve symptoms and prolong life. All those who are involved in the care of the young should be aware of these conditions. Failure to take notice when a young person reports a family history of sudden death demonstrates a serious lack of appropriate medical care. Screening for cardiomyopathy by experienced staff is accurate and readily available. Treatment improves symptoms and saves lives.