Interventional Pharmacology and Antithrombotic Therapy
Core concepts
Know antiplatelet pharmacology: aspirin (irreversible COX-1), P2Y12 inhibitors (clopidogrel prodrug with CYP2C19 variability; ticagrelor reversible; prasugrel irreversible), and GP IIb/IIIa inhibitors (abciximab, eptifibatide, tirofiban). Understand anticoagulants used in the cath lab: unfractionated heparin (monitor ACT), enoxaparin, bivalirudin (direct thrombin inhibitor, less bleeding, used in HIT), and fondaparinux. Master DAPT and triple therapy decisions, especially with atrial fibrillation and bleeding risk (HAS-BLED). Know reversal agents and periprocedural management of anticoagulation. Understand statin and beta-blocker roles post-MI.
Traps
- Forgetting clopidogrel is a prodrug requiring CYP2C19 activation; poor metabolizers have reduced response.
- Missing that prasugrel is contraindicated in prior stroke/TIA.
- Using bivalirudin without recognizing it is preferred in HIT.
- Overlooking that triple therapy (anticoagulant + DAPT) increases bleeding; minimize duration.
- Confusing ACT targets for heparin during PCI (typically 250–350 s).
Rule of thumb
In ACS/PCI, prefer ticagrelor or prasugrel over clopidogrel unless contraindicated. For AF plus PCI, use triple therapy briefly then drop to anticoagulant plus a single antiplatelet.
Worked example
A patient with AF on warfarin undergoes PCI. Rather than lifelong triple therapy, use triple therapy for the shortest feasible period, then transition to warfarin plus clopidogrel, and eventually warfarin alone.