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This is a clinician-written, evidence-based summary aligned to the USMLE Step 2 CK Content Outline. It is intended for medical students preparing for USMLE Step 2 CK. Management reflects current ACC/AHA, USPSTF, and APA guidelines. Always cross-reference with UpToDate, institutional protocols, and clinical judgment.
The Bottom Line
- Four statin benefit groups: (1) clinical ASCVD, (2) LDL >=190, (3) diabetes age 40-75, (4) 10-year ASCVD risk >=7.5% age 40-75
- Clinical ASCVD (secondary prevention): high-intensity statin (atorvastatin 40-80 mg or rosuvastatin 20-40 mg). Target LDL <70 mg/dL; add ezetimibe then PCSK9 inhibitor if not at goal
- Primary prevention: use pooled cohort equation (10-year ASCVD risk). >=20% = high-intensity statin. 7.5-19.9% = moderate-to-high intensity. 5-7.5% = consider if risk enhancers present
- LDL >=190 (likely familial hypercholesterolemia): high-intensity statin regardless of age or ASCVD risk
- Statin side effects: myalgias (most common, 5-10%), rhabdomyolysis (rare), new-onset diabetes (slight increase), elevated LFTs (check baseline, no routine monitoring)
Overview
Hyperlipidemia, particularly elevated LDL cholesterol, is a major modifiable risk factor for atherosclerotic cardiovascular disease. The 2018 ACC/AHA Cholesterol Guideline shifted from LDL targets to a risk-based approach centered on identifying the four statin benefit groups. However, the guideline also incorporated LDL thresholds for adding non-statin therapies in very high-risk ASCVD patients. Statins remain the cornerstone of therapy, with ezetimibe and PCSK9 inhibitors (evolocumab, alirocumab) as adjunctive agents.
Clinical Features
Symptoms
Typically asymptomatic — detected on routine lipid panel screening
Severe hypertriglyceridemia (>500 mg/dL): risk of acute pancreatitis (epigastric pain radiating to back)
Signs
Xanthelasma: yellowish plaques on eyelids (not specific for hyperlipidemia)
Tendon xanthomas: nodules on Achilles or extensor tendons (pathognomonic for familial hypercholesterolemia)
Corneal arcus: white ring around iris periphery (significant if age <45)
Eruptive xanthomas: yellow papules on trunk/buttocks (severe hypertriglyceridemia)
Investigations
First-line
Fasting lipid panelTotal cholesterol, LDL, HDL, triglycerides. Screening: adults >=20 every 4-6 years; earlier if risk factors. Non-fasting is acceptable for initial screening (TG may be elevated)
10-year ASCVD risk calculationPooled cohort equations: age, sex, race, total cholesterol, HDL, SBP, BP treatment, diabetes, smoking. Available at tools.acc.org
Second-line
Risk enhancers (if decision uncertain at 5-20% risk)Family history of premature ASCVD, metabolic syndrome, CKD, chronic inflammatory conditions (RA, SLE, HIV), South Asian ancestry, persistently elevated TG >=175, hs-CRP >=2, Lp(a) >=50 mg/dL, apoB >=130
Coronary artery calcium (CAC) scoreIf risk decision still uncertain after enhancers: CAC = 0 favors deferring statin; CAC >=100 (or >=75th percentile) favors statin. Most useful at borderline risk (5-20%)
Secondary causesTSH (hypothyroidism), BMP (nephrotic syndrome, CKD), LFTs (cholestatic liver disease), HbA1c (diabetes), medications (thiazides, beta-blockers, retinoids, estrogen)
Management
2018 ACC/AHA Cholesterol Guideline1
Statin benefit groups
- Group 1 — Clinical ASCVD (prior MI, stroke, PAD): high-intensity statin. If LDL remains >=70: add ezetimibe. If still >=70: add PCSK9 inhibitor (evolocumab, alirocumab)
- Group 2 — LDL >=190 mg/dL: high-intensity statin (likely familial hypercholesterolemia). Target >=50% LDL reduction. Add ezetimibe/PCSK9i if needed
- Group 3 — Diabetes, age 40-75: moderate-intensity statin at minimum. High-intensity if multiple risk factors or 10-year risk >=7.5%
- Group 4 — 10-year ASCVD risk >=7.5%, age 40-75: moderate-to-high intensity statin after clinician-patient discussion
2
Statin intensity
- High-intensity (>=50% LDL reduction): atorvastatin 40-80 mg, rosuvastatin 20-40 mg
- Moderate-intensity (30-49% reduction): atorvastatin 10-20 mg, rosuvastatin 5-10 mg, simvastatin 20-40 mg, pravastatin 40 mg
- Low-intensity (<30%): simvastatin 10 mg, pravastatin 10-20 mg (rarely used in guidelines)
3
Non-statin add-on therapies
- Ezetimibe 10 mg: reduces LDL ~15-20%. Add if statin alone insufficient (IMPROVE-IT trial in ACS)
- PCSK9 inhibitors (evolocumab, alirocumab): inject q2-4 weeks, reduce LDL ~50-60%. For very high-risk ASCVD or FH not at goal on max statin + ezetimibe (FOURIER, ODYSSEY trials)
- Bempedoic acid: oral ACL inhibitor, LDL reduction ~15-20%. Option for statin-intolerant patients (CLEAR Outcomes trial)
- Inclisiran: siRNA targeting PCSK9, dosed q6 months. Reduces LDL ~50%
4
Hypertriglyceridemia
- TG 150-499: lifestyle + optimize statin therapy. Icosapent ethyl (EPA) if TG 150-499 on statin + ASCVD or diabetes (REDUCE-IT trial — reduced CV events)
- TG >=500: immediate triglyceride-lowering to prevent pancreatitis. Fibrate (fenofibrate, gemfibrozil), omega-3 fatty acids, very low-fat diet
- Avoid gemfibrozil + statin combination (increased rhabdomyolysis risk). Fenofibrate is safer with statins
USMLE Step 2 CK Exam Tips
- 1Know the four statin benefit groups cold — this is tested frequently
- 2Clinical ASCVD = high-intensity statin always. LDL target <70 for secondary prevention
- 3LDL >=190 = high-intensity statin regardless of age or calculated risk (likely FH)
- 4Tendon xanthomas = pathognomonic for familial hypercholesterolemia
- 5Statins do NOT need routine LFT monitoring (check at baseline only). Statins are safe in chronic stable liver disease
- 6Statin myopathy: check CK only if symptomatic. Rhabdomyolysis is rare but suspect if severe myalgias + dark urine + CK >10x ULN
- 7PCSK9 inhibitors: for very high-risk ASCVD not at LDL goal despite max statin + ezetimibe
- 8Icosapent ethyl (EPA): reduces CV events in statin-treated patients with elevated TG (REDUCE-IT). This is newer and high-yield
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