Inherited heart conditions are the most common cause of sudden cardiac death in those under the age of 35 and the leading cause of non-traumatic death in young athletes. In many cases the first manifestation of an inherited cardiomyopathy can be a sudden cardiac arrest. Other presentations include chest pain or breathlessness during exertion, palpitations and syncope. Hypertrophic cardiomyopathy is the most common inherited heart disease affecting 1 in 500 of the population. Some patients may exhibit severe left ventricular hypertrophy, others may show nothing more than an abnormal ECG.