A 48-year-old man has a myocardial infarction despite total cholesterol of 180 mg/dL. His father had a similar event at age 45. Lipid fractionation shows elevated lipoprotein(a). The increased cardiovascular risk conferred by lipoprotein(a) is best explained by its structural similarity to which molecule, through which it impairs thrombolysis?

• A Tissue plasminogen activator
• B Vitamin K dependent clotting factors
• C Antithrombin III
• D Plasminogen ✓

Explanation

Lipoprotein(a) consists of an LDL particle covalently linked to apolipoprotein(a), whose sequence closely mimics plasminogen. By competing with plasminogen for binding on fibrin and endothelial surfaces, apo(a) interferes with plasmin generation and thereby reduces intravascular fibrinolysis, promoting thrombus persistence on disrupted plaques. It is an independent, genetically determined risk factor for premature atherosclerotic events and does not act via antithrombin or vitamin K pathways.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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