Lp(a) as a Risk Factor for Peripheral Artery Disease: Context Is Everything

Elevated plasma concentrations of Lp(a) (lipoprotein(a)) are an independent and causal risk factor for the development of atherosclerotic cardiovascular diseases, including peripheral artery disease (PAD). Although proatherosclerotic, proinflammatory, procalcific, and prothrombotic effects have been attributed to Lp(a), the precise pathogenic mechanisms by which Lp(a) contributes to these disorders are unclear. Moreover, whether Lp(a) contributes in different ways to atherosclerotic cardiovascular diseases in different vascular sites has not been explored. In particular, PAD involves atherosclerotic plaque rupture and subsequent thrombosis in vessels above the knee, but medial arterial calcification leading to vessel stiffness and thrombosis below the knee; the significance of Lp(a) in these contexts is unclear. Elevated Lp(a) is associated with the spectrum of PAD outcomes, including incident claudication, PAD progression, lower limb revascularization, restenosis, major adverse leg events, including limb amputation, and death and hospitalization due to PAD. Overall, elevated Lp(a) is as potent a risk factor for PAD as it is for coronary artery disease. Reducing Lp(a) to mitigate risk of PAD and to treat patients with PAD, therefore, remains a substantial unmet clinical need, although studies are underway to assess the efficacy of RNA-directed Lp(a)-lowering therapies in preventing atherosclerotic cardiovascular disease events. Mounting clinical trials of these therapies to specifically address their effect on PAD events is the next key step.