The original classification described three types which have become established clinical entities and this terminology has been preserved. Histology is nonspecific. Presentation is usually with heart failure which is often progressive. Arrhythmias, thromboembolism and sudden death are common and may occur at any stage. Typically, the left ventricular volume is normal or reduced.
Systolic gradients are common.
Familial disease with autosomal dominant inheritance predominates. Mutations in sarcomeric contractile protein genes cause disease. Arrhythmias and premature sudden death are common. Increased interstitial fibrosis may be present. Familial disease is common with autosomal dominant inheritance and incomplete penetrance, a recessive form is described.