HDL Function Versus Small Dense LDL: Cardiovascular Benefits and Implications.

High-density lipoprotein (HDL) and small dense low-density lipoprotein (sdLDL) represent two critical yet contrasting components in lipid metabolism and cardiovascular risk modulation. While HDL has traditionally been viewed as cardioprotective due to its role in reverse cholesterol transport and anti-inflammatory effects, emerging evidence emphasizes that HDL functionality-rather than concentration alone-is pivotal in atheroprotection. Conversely, sdLDL particles are increasingly recognized as highly atherogenic due to their enhanced arterial penetration, oxidative susceptibility, and prolonged plasma residence time. This review critically examined the physiological roles, pathological implications, and therapeutic interventions targeting HDL function and sdLDL burden. Lifestyle modifications, pharmacologic agents including statins, fibrates, PCSK9 inhibitors, and novel therapies such as icosapent ethyl were discussed in the context of their effects on HDL quality and sdLDL reduction. Additionally, current clinical guidelines were analyzed, highlighting a paradigm shift away from targeting HDL-C levels toward apoB-driven risk reduction. Although HDL-targeted therapies remain under investigation, the consensus supports focusing on lowering apoB-containing lipoproteins while leveraging lifestyle strategies to improve HDL functionality. In the setting of heart failure, particularly with preserved ejection fraction (HFpEF), alterations in HDL composition and elevated sdLDL levels have been linked to endothelial dysfunction and systemic inflammation, further underscoring their relevance beyond atherosclerosis. A comprehensive understanding of HDL and sdLDL dynamics is essential for optimizing cardiovascular prevention strategies.