If it were not for the great variability among individuals, medicine might as well be a science and not an art. (Sir William Osler, 1892)

The sudden unexpected death of an individual at any age has a profound effect on the family and the wider community and this is particularly significant when it affects a young person. Hypertrophic cardiomyopathy remains one of the common causes of sudden cardiac death (SCD) in young individuals.1 In a cohort of 744 patients with hypertrophic cardiomyopathy from the USA and Italy, where 86 (12%) died over an 8 (SD±7) year period of follow-up, three main modes of death were identified: sudden and unexpected (found mainly but not exclusively in adolescents and young adults); heart failure; and stroke, usually associated with the development of atrial fibrillation.2 The most common underlying pathophysiological mechanism leading to sudden death is the development of ventricular tachyarrhythmias occurring on a background of myocyte disarray, interstitial fibrosis, and arteriolar changes with contributory ischaemic and autonomic effects.1 Abnormalities of intercalated discs and gap junctions have also been reported.3 An integral component of clinical investigation and management of patients with hypertrophic cardiomyopathy is the assessment of risk of sudden death, as those individuals with a perceived significantly increased risk may be considered for prophylactic implantable cardioverter defibrillator (ICD) implantation.

The estimated prevalence of hypertrophic cardiomyopathy is 1 in 500 but many individuals have a subclinical phenotype. Many patients with this condition have an excellent prognosis similar to that of the background population and these individuals are characterised by the absence of major risk factors for sudden death.4 Several risk factors for sudden death have been identified.1 ,5 The generally accepted major risk factors include: family history of sudden death; unexplained syncope; non-sustained ventricular tachycardia (NSVT) on …