Chapter 19: Hyperlipidemia – Managing Cholesterol with Medication

Hyperlipidemia – Managing Cholesterol with Medication comprehensively defines hyperlipidemia (dyslipidemia) as a blood disorder characterized by elevated cholesterol levels, which serves as a major modifiable risk factor for the development of atherosclerotic cardiovascular disease (ASCVD). Etiologically, the condition commonly stems from a combination of genetic abnormalities affecting lipoprotein synthesis or clearance, and secondary factors like poor diet, obesity, specific medications, and systemic diseases such as diabetes or hypothyroidism. The underlying pathophysiology involves the accumulation and oxidation of low-density lipoprotein cholesterol (LDL-C, or "bad cholesterol") within the arterial intima, leading to macrophage ingestion and the formation of foam cells that constitute the initial fatty streak. Progression of these lesions results in fibrous plaque development, which, when unstable or ruptured, is the primary mechanism for acute cardiovascular events like myocardial infarction. Clinical management follows the framework of individualized risk assessment, utilizing the 2018 ACC/AHA guidelines, which prioritize intensive treatment based on a patient’s calculated 10-year ASCVD risk using Pooled Cohort Equations (PCE) and incorporating risk-enhancing factors and Coronary Artery Calcium (CAC) scores to refine borderline cases. Foundational treatment involves rigorous lifestyle modifications, encompassing diet, exercise, and smoking cessation, which can significantly improve lipid profiles. Pharmacologic intervention centers on HMG-CoA reductase inhibitors (statins), which block the rate-limiting step of hepatic cholesterol production and are grouped into four benefit categories based on risk. For patients who cannot achieve sufficient LDL-C reduction with maximal statin therapy, or those with intolerance, non-statin agents are used as add-on therapy, most notably cholesterol absorption inhibitors (ezetimibe) and the highly potent injectable PCSK9 inhibitors. Alternative agents include bile acid resins, niacin (often limited by adverse effects like flushing), and fibric acid derivatives, primarily reserved for patients with severely elevated triglycerides. Throughout therapy, monitoring parameters focus on achieving targeted LDL-C reduction goals and assessing for drug-related adverse events, particularly muscle symptoms (myopathy) and potential hepatotoxicity.