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Cardiomyopathy is defined as ‘a myocardial disorder in which the heart muscle is structurally and functionally abnormal, in the absence of coronary artery disease, hypertension, valvular disease and congenital heart disease sufficient to cause the observed myocardial abnormality’. 1 Hypertrophic cardiomyopathy (HCM) involves increased left ventricular wall thickness that is not solely explained by abnormal loading conditions (eg, hypertension, valve disease) and may include hypertrophy of the septum.1–3 There may also be associated mitral valve distortion, which, together with the hypertrophy of the septum, may lead to left ventricular outflow tract obstruction (LVOTO) with a pressure gradient between the left ventricle and the aorta.3 This occurs in around two-thirds of patients with HCM and is known as obstructive HCM (oHCM).2 In most cases, HCM results from a genetic mutation that causes alteration in cardiac sarcomere function.2 4 The prevalence of unexplained left ventricular hypertrophy is thought to be 1 in 500 adults (0.2%) in the general population.2