Screening for arrhythmia and sudden cardiac death

Screening for arrhythmia and sudden death has been outlined in the National Service Framework. Key points from this guidance include:

• first degree relatives of victims of sudden cardiac death who died under the age of 40 years old are referred to a heart rhythm specialist
• evaluation of families who may have an inherited cardiac disease should take place in a dedicated clinic with staff who are trained in the diagnosis, management and support for these families. Genetic testing and further investigations are available if appropriate
• any child with recurrent loss of consciousness, collapse associated with exertion, atypical seizures with a normal EEG or with any documented arrhythmias is referred to a paediatric cardiologist

In the context of sudden cardiac death:

1. Family evaluation - this consists of two parts
   1. First, the background history of the proband (victim of sudden death) should be elicited including preceeding symptoms, previous medical history and circumstances of death
   2. Second, the family history must be established including any histories of unexplained syncope, sudden death, muscle weakness or congenital deafness
   3. Each first-degree relative should have their personal history taken and undergo an examination. The National Service Framework suggests that screening should be undertaken in all first-degree relatives (parents, siblings and children) of anyone who has died under 40 years of age from an inherited cardiac condition or unexplained cardiac death (these individuals should be referred to a cardiac rhythm expert). The following investigations are often undertaken: Depending on these results, further specialist tests are undertaken relating to arrhythmogenic right ventricular cardiomyopathy, Burgada syndrome and Wolff-Parkinson-White syndrome:
      • 12 lead ECG (with signal averaging)
      • echocardiogram
        • the screening should be a minimum of an ECG and an echocardiogram (1)
      • Holter monitor (24 hours or longer)
      • cardio-pulmonary exercise ECG test
      • cardiac magnetic resonance imaging
      • ajmaline provocation test
      • adenosine provocation testing
2. Genetic testing - genotyping of families with long QT syndrome, Brugada syndrome and hypertrophic obstructive cardiomyopathy is possible allowing confirmation of diagnosis, clarification of carrier status and even guidance of therapy. The limited knowledge of the full genetics of these disorders makes a negative result unhelpful.
3. Further management - it is reasonable to review those families without a diagnosis in order to detect conditions that have labile ECG syndrome (for example long QT syndrome, Brugada syndrome). If a diagnosis has been made then advice on testing of other relatives is appropriate. Further investigation may be necessary (e.g. electrophysiological study in Brugada syndrome) and appropriate treatments made available (e.g. betablockers and/or implantable cardioverter defibrillators in long QT syndrome).

Notes:

• screening with respect to hypertrophic obstructive cardiomyopathy:
  • children below the age of 10 years at risk of developing a particular disease should be screened with an ECG and echocardiogram every 3-5 years. If there is a family history of hypertrophic obstructive cardiomyopathy then the period of screening should be every 6-12 months from the age of 10 years, when the disease is at the most risk of developing
  • from the age of 16 to 20 years then annual screening is advised. If there is are signs of late-onset hypertrophic cardiomyopathy in the family then there should be continued screening at 5 yearly intervals after the age of 20 years. If others wish to continue to be screened, and the necessary resources are available, then five yearly screening is recommended
  • screening intervals are not formally established in the other cardiomyopathies but are tailored to the pattern of disease expression within a family

Reference:

1. The National Service Framework for Arrhythmias and Sudden Death 2005.
2. Pulse (May 28th 2005): 54-61.
3. British Heart Foundation (Factfile 04/2002). Sudden cardiac death in young people.