Cardiology · Lipid Disorders
The facts most likely to be tested
High-intensity statins (atorvastatin 40-80 mg or rosuvastatin 20-40 mg) are the first-line therapy for patients with clinical atherosclerotic cardiovascular disease (ASCVD).
Familial hypercholesterolemia is caused by an autosomal dominant mutation in the LDL receptor gene, leading to severely elevated LDL-C levels and premature coronary artery disease.
Ezetimibe is the preferred second-line agent to add to statin therapy for patients who fail to reach LDL-C goals despite maximal tolerated statin therapy.
PCSK9 inhibitors (e.g., evolocumab) are indicated for patients with familial hypercholesterolemia or high-risk ASCVD who remain above target LDL-C levels despite statin and ezetimibe therapy.
Fibrates are the treatment of choice for patients with severe hypertriglyceridemia (>500 mg/dL) to reduce the risk of acute pancreatitis.
Tendon xanthomas and corneal arcus are pathognomonic physical exam findings associated with severe familial hypercholesterolemia.
Statin-associated muscle symptoms (SAMS), including myalgia or myositis, require checking creatine kinase (CK) levels and potentially switching to a different statin or lowering the dose.
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A 45-year-old male presents for a routine physical. He has a family history of myocardial infarction in his father at age 42. Physical examination reveals bilateral corneal arcus and thickened Achilles tendons. His fasting lipid panel shows a total cholesterol of 340 mg/dL and an LDL-C of 260 mg/dL. He has no prior history of cardiovascular disease.
What is the most appropriate initial pharmacologic management for this patient?
High-intensity statin therapy
The patient's clinical presentation of tendon xanthomas and severe LDL elevation is diagnostic for familial hypercholesterolemia, which requires immediate initiation of high-intensity statins to prevent premature ASCVD.
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Etiology / Epidemiology
Primary causes are genetic (familial); secondary causes include diabetes, hypothyroidism, and alcohol use.
Clinical Manifestations
Often asymptomatic; look for xanthelasma, tendon xanthomas, and corneal arcus.
Diagnosis
Fasting lipid panel is the gold standard; LDL > 190 mg/dL warrants high-intensity therapy.
Treatment
Statins are first-line; pregnancy is a strict contraindication.
Prognosis
Primary goal is reduction of ASCVD risk; monitor ALT/AST and CK levels.
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Epidemiology & Etiology
Hyperlipidemia results from a combination of polygenic inheritance and lifestyle factors like high saturated fat intake. Secondary causes are common and must be ruled out, specifically hypothyroidism, nephrotic syndrome, and obstructive liver disease. Screening is recommended for all adults starting at age 20.
Pertinent Anatomy
Lipid deposition occurs in the tunica intima of arterial walls, leading to atherosclerotic plaque formation. Peripheral deposits occur in the eyelids (xanthelasma) and Achilles tendons (xanthomas) due to high circulating LDL.
Pathophysiology
Elevated ApoB-containing lipoproteins infiltrate the arterial wall, where they undergo oxidation. Macrophages ingest oxidized LDL to become foam cells, forming the fatty streak. Over time, this triggers a chronic inflammatory response, leading to fibrous cap formation and eventual plaque rupture.
Clinical Manifestations
Most patients are asymptomatic until a cardiovascular event occurs. Physical exam may reveal xanthelasma (yellow eyelid plaques) or tendon xanthomas. Acute pancreatitis is a red-flag symptom of severe hypertriglyceridemia (> 1000 mg/dL).
Diagnosis
The fasting lipid panel (8-12 hours) is the diagnostic standard. LDL-C > 190 mg/dL is diagnostic of severe primary hypercholesterolemia. Calculate the ASCVD 10-year risk score to guide initiation of pharmacotherapy.
Treatment
HMG-CoA reductase inhibitors (Statins) are the first-line treatment for all risk groups. Pregnancy and active liver disease are absolute contraindications. If LDL remains elevated, add ezetimibe or PCSK9 inhibitors.
Prognosis
The primary outcome is the prevention of myocardial infarction and stroke. Patients require baseline LFTs and monitoring for myopathy or rhabdomyolysis if muscle pain develops.
Differential Diagnosis
Hypothyroidism: elevated TSH
Nephrotic syndrome: proteinuria and edema
Diabetes mellitus: elevated HbA1c
Obstructive liver disease: elevated alkaline phosphatase
Familial hypercholesterolemia: LDL > 190 mg/dL