USMLE/COMLEX 3 - Atherosclerosis

Here are key facts for USMLE Step 3 & COMLEX-USA Level 3 from the Atherosclerosis Tutorial, as well as points of interest at the end of this document that are not directly addressed in this tutorial but should help you prepare for the boards. See the tutorial notes for further details and relevant links.

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1. Atherosclerosis is the major pathophysiological mechanism behind coronary artery disease (CAD), myocardial infarction, ischemic stroke, peripheral artery disease (PAD), and aortic aneurysms. 2. Clinical manifestations include:

• Angina (stable and unstable)
• Myocardial infarction
• Transient ischemic attacks (TIAs) and stroke
• Claudication and critical limb ischemia
• Aortic dissection or rupture

3. Plaque rupture and thrombosis are the key mechanisms for acute events like STEMI or embolic stroke. 4. Use the ASCVD 10-year risk calculator for all adults age 40–75 to guide statin initiation. 5. High-intensity statins are indicated in:

• Clinical ASCVD (e.g., prior MI, stroke, PAD)
• LDL ≥190 mg/dL
• Age 40–75 with diabetes and LDL ≥70 mg/dL
• ASCVD risk ≥7.5%

6. Moderate-intensity statins are appropriate if risk is 5%–7.5% or patient is older or at risk for statin intolerance. 7. For patients with statin intolerance, consider ezetimibe or PCSK9 inhibitors. 8. Check lipid panel 4–12 weeks after starting statin therapy, then every 6–12 months. 9. Monitor for statin side effects: elevated liver enzymes, myopathy, and new-onset diabetes (rare but tested). 10. Focus on LDL reduction targets (e.g., ≥50% decrease with high-intensity statin).

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1. Confirm atherosclerotic burden using:

• Coronary calcium scoring in borderline-risk patients
• Carotid duplex ultrasound for stroke/TIA or asymptomatic bruits
• Ankle-brachial index (ABI) for claudication or PAD
• CT angiography or MRA for vascular assessment in limb ischemia

2. Elevated CRP is an inflammatory marker linked to cardiovascular risk; it may support statin initiation in intermediate-risk patients. 3. Additional labs: HbA1c, fasting glucose, and renal function should be monitored to guide comprehensive cardiovascular risk management. 4. Emphasize lifestyle modification for all patients:

• Smoking cessation
• Diet (Mediterranean or DASH)
• Exercise (150 minutes/week)
• Weight loss if overweight
• Blood pressure and glucose control

5. Antiplatelet therapy is indicated for secondary prevention (e.g., aspirin 81 mg). 6. Do not use aspirin for primary prevention unless ASCVD risk is >10% and bleeding risk is low. 7. Watch for erectile dysfunction, silent ischemia, or cognitive changes as possible atherosclerotic presentations. 8. In older adults, consider atypical symptoms of ischemia such as dyspnea or fatigue without chest pain. 9. Use shared decision-making for initiating statins in low-to-intermediate risk patients.

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1. Diabetes mellitus is considered a cardiovascular disease equivalent; all diabetics 40–75 years old should receive moderate-to-high intensity statin therapy regardless of LDL. 2. In patients with chronic kidney disease (CKD) (but not on dialysis), statin use is indicated to lower cardiovascular risk. 3. HIV-positive patients are at increased atherosclerotic risk and may require earlier intervention. 4. Avoid simvastatin with protease inhibitors due to increased risk of statin toxicity. 5. Continue statins in the perioperative period for patients undergoing non-cardiac surgery. 6. Consider preoperative cardiac evaluation in patients with known CAD or multiple risk factors undergoing vascular procedures. 7. In patients with LDL >70 mg/dL despite maximal statin therapy, consider adding ezetimibe or PCSK9 inhibitor, especially in clinical ASCVD. 8. In cases of statin-induced myopathy, hold therapy, recheck CK, then resume at lower dose or change agent. 9. Use alirocumab or evolocumab (PCSK9 inhibitors) in patients with familial hypercholesterolemia or very high risk ASCVD.