A 62-year-old man with acute coronary syndrome (NSTEMI) is being managed with dual antiplatelet therapy and anticoagulation. Regarding the pharmacology of anticoagulants, all of the following statements are true EXCEPT:

Explanation

## Anticoagulants in Acute Coronary Syndrome **Key Point:** Fondaparinux, despite being an effective anticoagulant, is **NOT recommended as monotherapy** in acute coronary syndrome. It carries an increased risk of catheter thrombosis when used alone during percutaneous coronary intervention (PCI) and must be combined with antiplatelet therapy and, in many cases, additional anticoagulation (UFH or enoxaparin during PCI). ### Anticoagulant Comparison | Agent | Half-life | Reversibility | Renal Clearance | ACS Role | |-------|-----------|---------------|-----------------|----------| | UFH | 60–90 min | Rapid (protamine) | Hepatic | Preferred in renal failure; reversible | | LMWH | 4–6 hours | Partial (protamine) | Renal (40–50%) | Standard in NSTEMI; caution if eGFR <30 | | Fondaparinux | 17–21 hours | None | Renal (100%) | **NOT monotherapy in ACS**; risk of stent thrombosis | | Dabigatran | 12–17 hours | Idarucizumab | Renal (80%) | Not used acutely in ACS | | Warfarin | 36–42 hours | Vitamin K, FFP | Hepatic | Long-term anticoagulation post-ACS | **High-Yield:** The fondaparinux–ACS limitation is a frequent NEET PG trap. Students often remember fondaparinux as an anticoagulant and assume it can replace heparin in ACS, but guideline evidence (ESC, ACC/AHA) explicitly recommends against monotherapy due to stent thrombosis risk. **Clinical Pearl:** In a patient on fondaparinux undergoing PCI, UFH must be added during the procedure to prevent catheter and stent thrombosis. This is a critical bedside rule. **Warning:** Do not confuse fondaparinux's efficacy in VTE prophylaxis (where it IS monotherapy) with its role in acute ACS (where it is NOT). ### Why Other Statements Are Correct 1. **UFH vs. LMWH half-life:** UFH (60–90 min) is indeed shorter than LMWH (4–6 hours), making UFH preferable when rapid reversal is needed (e.g., bleeding, urgent surgery). 2. **Dabigatran renal excretion:** Dabigatran is 80% renally excreted and requires dose reduction (e.g., 75 mg BD) in severe renal impairment (eGFR <30 mL/min). 3. **Warfarin mechanism:** Warfarin inhibits vitamin K-dependent factors (II, VII, IX, X) via γ-carboxylation inhibition and requires INR monitoring due to narrow therapeutic index and drug/food interactions.