An additional challenge to diagnosis is posed by the fact that mutations in genes encoding sarcomeric proteins are not found in up to a third of patients with HCM 9 and the diagnosis remains a clinical rather than a ‘genetic’ one. 2,7,8 This can create difficulties in terms of differentiation from other causes of LVH such as hypertension or physiological adaptations to exercise seen in athletes. 7 However, HCM can be phenotypically heterogeneous and also manifest with mild LVH, concentric LVH and without some of these typical characteristics, whilst retaining the increased risk for sudden death. 6 Echocardiography is usually diagnostic of the condition in the presence of features, such as maximal left ventricular (LV) wall thickness ≥15 millimetres (mm), asymmetric septal hypertrophy, apical HCM or systolic anterior motion of the mitral valve, and septal/posterior wall thickness ratio >1.3. 5 Other characteristics include impaired sarcomere calcium cycling, inefficient energy usage and microvascular dysfunction. 3,4 Typical pathological features of the condition include hypertrophy, fibrosis and cardiomyocyte disarray. 2 The condition was the first cardiomyopathy to be causally linked with a genetic mutation, and subsequent studies to date have shown that a specific mutation affecting the sarcomere or sarcomere-associated proteins can be identified in more than half the cases. 1 It can be defined as a condition that is typified by unexplained left ventricular hypertrophy (LVH) in the absence of other cardiac or non-cardiac conditions that could produce hypertrophy of similar proportions.

Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiovascular disorder worldwide with a prevalence of 1 in 500 in the general population.

Pathological hypertrophy examples