9.3 Anticoagulation & ACT Targets

9.3 Anticoagulation & ACT Targets

Quick Answer: Activated clotting time (ACT) guides unfractionated heparin (UFH) anticoagulation in the cath lab. Commonly cited targets: ~200–250 sec for diagnostic catheterization, ~250–300 sec for PCI with GP IIb/IIIa, and ~300+ sec for PCI without GP IIb/IIIa. Know heparin dosing, bivalirudin alternatives, P2Y12 loading, ACT monitoring, and reversal principles.

Anticoagulation prevents intracardiac and intracoronary thrombus during catheters, guidewires, and stent deployment—but excess anticoagulation drives access-site bleeding, retroperitoneal hemorrhage, and stroke from uncontrolled hypertension after sheath pull. RCIS candidates must fluently translate procedure type + anticoagulant choice → ACT goal → monitoring interval → closure criteria.

What ACT Measures

The activated clotting time (ACT) is a bedside whole-blood clotting assay (celite or kaolin activator) reporting seconds until clot formation. It is the primary monitor for UFH effect in the cath lab because it returns results in 2–3 minutes—fast enough to adjust boluses during PCI.

Always record activator type (celite vs kaolin)—values are not interchangeable between methods.

Diagnostic vs Interventional ACT Targets

These ranges appear throughout CCI prep materials and ACC/AHA/SCAI practice patterns. Institutional protocols may vary slightly—follow your lab's written standard—but exam items use the commonly cited numbers:

Exam shorthand many candidates memorize:

• Diagnostic: 200–250
• PCI + IIb/IIIa: 250–300
• PCI without IIb/IIIa: 300+

If ACT is below target mid-PCI, anticipate additional UFH bolus per physician order and repeat ACT—never assume one bolus lasts the entire case.

Heparin Dosing and Monitoring Workflow

1. Confirm no HIT history and no active major bleeding.
2. Administer bolus (weight-based for PCI).
3. Draw ACT 3–5 minutes after bolus (allows circulation).
4. Document time, dose, ACT, and repeat per protocol.
5. Communicate sub/supratherapeutic values to the operator before continuing high-risk steps (stent deployment, prolonged equipment in LV).

Low-molecular-weight heparin (LMWH) is not monitored with ACT and is not the standard procedural anticoagulant for PCI in most US cath labs—do not confuse exam distractors.

Bivalirudin (Direct Thrombin Inhibitor)

Bivalirudin is a recombinant hirudin analog with predictable anticoagulation, short half-life, and no protamine reversal.

RCIS items may ask which agent to anticipate when platelets crashed after recent heparin and HIT is suspected—answer bivalirudin (or argatroban), and stop all heparin including line flushes.

GP IIb/IIIa Inhibitors (Context for ACT)

Abciximab, eptifibatide, tirofiban block final common pathway of platelet aggregation. Routine use has declined with potent P2Y12 inhibitors and improved stent platforms, but CCI still tests ACT interaction:

• With IIb/IIIa, lower ACT target (250–300) because dual pathway blockade ↑ bleeding if ACT is pushed to 350+.
• Recognize thrombocytopenia and mucosal bleeding as class effects.

P2Y12 Inhibitors and Dual Antiplatelet Therapy (DAPT)

P2Y12 agents (clopidogrel, prasugrel, ticagrelor) are antiplatelet, not anticoagulants—ACT does not measure their effect. They are essential for stent thrombosis prevention and appear in anticoagulation cross-cut RCIS items.

Aspirin (162–325 mg loading, then 81 mg daily) remains foundation of DAPT. Confirm loading occurred before or during PCI when stenting is planned.

Cross-cut exam trap: A question about ACT 280 sec may still require recognizing inadequate platelet inhibition if no P2Y12 load was given—anticoagulation alone does not prevent stent thrombosis.

ACT at Case End: Sheath Removal and Reversal

After femoral PCI, ACT must fall before manual compression or closure device deployment:

• Many protocols: ACT <150–180 sec or ≥4–6 h since last heparin if ACT unavailable.
• Protamine 1 mg per 100 units UFH in prior hour (max ~50 mg) partially reverses UFH; give slowly—risk hypotension, bradycardia, pulmonary hypertension.

Radial access often permits early ambulation with patent hemostasis—still document ACT if protocol requires before transfer.

Special Populations

Quick Reference: Anticoagulation Decision Tree

Procedure planned?
├── Diagnostic cath → UFH (often 2–5k U or 50 U/kg) → ACT ~200–250
├── PCI ± IIb/IIIa
│   ├── IIb/IIIa YES → UFH 70–100 U/kg → ACT ~250–300
│   └── IIb/IIIa NO  → UFH 70–100 U/kg → ACT ~300+
├── HIT suspected/confirmed → Bivalirudin (no heparin)
└── Stent placed → Confirm aspirin + P2Y12 load (ACT does not assess DAPT)

RCIS Documentation Checklist

• Heparin dose, time, route, weight used for calculation
• ACT values with activator type and clock time
• P2Y12 agent, dose, time (and aspirin)
• Bivalirudin bolus/infusion rates if used
• Protamine dose/time if given
• ACT prior to sheath removal or hemostasis device deployment

Mastering ACT targets links Domain B diagnostic pharmacology with interventional anticoagulation—the cross-cut CCI uses to see whether you can keep a patient therapeutically anticoagulated during stenting and safely hemostatic afterward.