This multicentre , randomised , double-blind , placebo-controlled trial was undertaken at @ sites ( most of which were specialised lipid clinics , mainly attached to academic institutions ) in Australia , Asia , Europe , New Zealand , North America , and South Africa between Feb @ and Dec @ , @ eligible patients ( @-@ years of age ) , who met clinical criteria for heterozygous familial hypercholesterolaemia and were on stable lipid-lowering therapy for at least @ weeks , with a fasting LDL cholesterol concentration of @ mmol/L or higher , were randomly allocated in a @:@:@:@ ratio to receive subcutaneous evolocumab @ mg every @ weeks , evolocumab @ mg monthly , or subcutaneous placebo every @ weeks or monthly for @ weeks .