Residual lipid risk in atherosclerotic cardiovascular disease

Despite significant advances in lipid-lowering therapeutics, residual lipid risk persists in patients with or at risk of atherosclerotic cardiovascular disease (ASCVD), even after optimizing low-density lipoprotein (LDL) cholesterol. Emerging evidence highlights the role of non-LDL cholesterol fractions, such as remnant cholesterol, lipoprotein(a) [Lp(a)], apolipoprotein B (apoB), and non-high-density lipoprotein (HDL) cholesterol, as key contributors to residual ASCVD risk. Remnant cholesterol, Lp(a), and LDL cholesterol represent three independent lipoprotein species causing ASCVD, while apolipoprotein B (apoB) and non-HDL cholesterol integrate the other three variables. Thus, clinically interpreting elevated apoB and non-HDL cholesterol is potentially complicated since remnants, Lp(a), and LDL cause ASCVD by different mechanisms and by varying proportions in different patients. Indeed, recent research into the pathophysiology of lipid-driven atherogenesis and development of ASCVD has revealed novel mechanisms that in turn suggest new therapeutic strategies targeting non-LDL lipid components. Elevated remnant cholesterol jointly with elevated LDL cholesterol contributes to arterial wall cholesterol deposition, plaque development, and ASCVD endpoints. Furthermore, the additional triglyceride content in remnant particles may theoretically promote intimal inflammation and possibly plaque rupture and erosion, independently contributing to atherogenesis and ASCVD. The lipid component and pro-inflammatory properties of Lp(a) could similarly contribute directly to atherosclerotic plaque development and ASCVD. In addition, the homology with plasminogen of the defining apolipoprotein(a) moiety of Lp(a) has long been speculated to confer anti-fibrinolytic and pro-thrombotic properties that could produce more severe ASCVD outcomes independent of atherogenesis. This review explores the evolving understanding of residual lipid risk in ASCVD, practical guidance for clinicians today, recent advances in therapeutic interventions, and their implications for clinical practice, aiming to optimize lipid management beyond LDL cholesterol reduction today and in the future.