Low HDL—The Challenge

The main function of high-density lipoprotein (HDL) is to remove low-density lipoprotein (LDL) from blood vessels through reverse cholesterol transport. In addition, HDL has anti-inflammatory and antioxidant properties. Low HDL level is an independent risk factor for development of coronary artery disease. To manage patients with low HDL levels, general measures such as lifestyle modification, controlling acute metabolic syndrome, and participating in regular endurance exercise are essential. Smoking cessation is a must, and it will often improve HDL levels by 5% to 10%. While statin therapy is the backbone therapy for controlling LDL levels, it also results in elevation of HDL levels by at least 5%. Specific pharmacologic interventions to improve HDL level and function have been disappointing. Cholesteryl ester transfer protein (CETP) is the key metabolic pathway to transfer HDL to LDL; thus, CETP inhibitors result in elevation of HDL levels. Several products were tested in large controlled studies, such as dalcetrapib and evacetrapib; neither resulted in any clinical benefit. Anacetrapib only resulted in very limited benefit and is no longer under active development. The most recent study utilized apolipoprotein A1 infusion in high-risk patients shortly after acute myocardial infarction. There was no benefit in the primary end point of myocardial infarction, stroke, or death. In patients with low HDL, a strategy of having LDL as low as can be possibly achieved may be the most appropriate approach.