Approximately 35 million people worldwide suffer from heterozygous familial hypercholesterolaemia (HeFH), a condition characterized by genetically determined life-long elevation of plasma low-density lipoprotein cholesterol (LDL-C). One in three of these patients also inherit an elevated plasma concentration of lipoprotein (a) [Lp(a)], a lipoprotein particle with atherogenic, inflammatory and prothrombotic properties. Accordingly, the combination of high plasma LDL-C and Lp(a) can markedly accelerate premature atherosclerotic cardiovascular disease (ASCVD). Neither statin nor ezetimibe lowers Lp(a), so that FH patients with high Lp(a) remain at high residual risk of ASCVD. PCSK9 monoclonal antibodies are indicated for HeFH patients not at guideline-recommended LDL-C target, but only lower Lp(a) concentration by 15-30%. Recent trials employing apo(a) antisense therapy show more potent (up to 90%) reductions in plasma Lp(a). The combination of PCSK9 inhibitor and apo(a) antisense therapy appears the optimal strategy for mitigating residual risk of ASCVD in HeFH patients with high Lp(a).