Genomics in general practice

Sudden arrhythmic death syndrome

Last revised: 30 Nov 2018

Practice point

Genetic heart disorders are an important cause of sudden arrhythmic death syndrome (SADS) in people <40 years of age.1

In many cases, the death of a young person in the family can often be the first sign of a potential genetic heart disease within that family.2 Identifying a genetic basis of sudden cardiac death is vital in being able to accurately manage families.3
 

SADS is an umbrella term to describe unexpected deaths in young people (usually 40 years of age), whose cause of death following post mortem examination is ‘undetermined’ or ‘unascertained’.3

The most common SADS conditions include genetic arrhythmia syndromes such as long QT syndrome, catecholaminergic polymorphic ventricular tachycardia (CPVT) and Brugada syndrome.

These conditions follow an autosomal dominant inheritance pattern. Therefore, first-degree relatives (ie parents, siblings, children) of an individual who has a genetic arrhythmogenic disorder are at a 50% risk of also having a gene variant for the condition, and thus, at risk of developing the condition. All these conditions show considerable clinical variability within families and have incomplete penetrance.1,4,5

Of interest are individuals presenting with:3

  • any first-degree relatives with unexplained sudden cardiac death <40 years of age
  • episodes of unexplained syncope
  • syncope or seizures during exercise, excitement or startle.

Collect a comprehensive family history (three generations), noting any relatives with the features above.3

Genetic testing can be arranged through a genetics clinic if appropriate.6 There is currently no Medicare Benefits Schedule (MBS) rebate for testing.

Refer those with relevant family history to cardiology for cardiac screening tests, and to a cardiac genetics clinic for risk assessment.2

Familial screening is vital when a genetic heart condition has been confirmed in an index case.

Emotional and psychological support is vital for families where sudden cardiac death has occurred and referrals for grief counselling should be offered.2

  1. Cardiac Society of Australia and New Zealand. Cardiac genetic investigation of young sudden unexplained death and resuscitated out of hospital cardiac arrest. Sydney: CSANZ, 2011 [Accessed 22 December 2017].
  2. Ingles J, Semsarian C. Sudden cardiac death in the young: A clinical genetic approach. Intern Med J 2007;37(1):32–37. [Accessed 22 December 2017].
  3. Priori SG, Blomström-Lundqvist C, Mazzanti A, et al. 2015 ESC Guidelines for the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death: The Task Force for the Management of Patients with Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death of the European Society of Cardiology (ESC). Eur Heart J 2015;36(41):2793–867. [Accessed 22 December 2017].
  4. Alders M, Christiaans I. Long QT syndrome. GeneReviews. Seattle, WA: University of Washington, 2003 [Accessed 22 December 2017].
  5. Brugada R, Campuzano O, Sarquella-Brugada G, et al. Brugada syndrome. GeneReviews. Seattle, WA: University of Washington, 2005 [Accessed 22 December 2017].
  6. Cardiac Society of Australia and New Zealand. Guidelines for genetic testing of inherited cardiac disorders. Sydney: CSANZ, 2011 [Accessed 22 December 2017].
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