In this multicentre , randomised , double-blind , placebo-controlled , phase @ study , patients aged @-@ years with a genotype-confirmed or clinical diagnosis of heterozygous familial hypercholesterolaemia , on optimum lipid-lowering treatment for at least @ weeks , and with an LDL-C concentration of @ mmol/L or higher without cardiovascular disease or @ mmol/L or higher with cardiovascular disease from @ lipid clinics across nine countries were eligible .