3.4 Management of Patients on Anticoagulants & Antiplatelet Therapy

3.4 Management of Patients on Anticoagulants & Antiplatelet Therapy

Managing dental patients taking antithrombotic medications requires balancing the risk of perioperative oral bleeding against the potentially catastrophic risk of thromboembolism (stroke, deep vein thrombosis, pulmonary embolism, myocardial infarction) if medications are temporarily discontinued. Current Australian clinical guidelines strongly support continuing antithrombotic therapy for minor oral surgical procedures while employing local haemostatic measures.

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Haemostasis & Thromboembolic Risk Assessment

Haemostasis involves vascular constriction, primary platelet plug formation (primary haemostasis), and secondary activation of the coagulation cascade yielding a stable fibrin clot (secondary haemostasis).

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|                                 MECHANICAL HAEMOSTASIS PATHWAY                                    |
|                                                                                                   |
|  Vascular Injury ===> Platelet Adhesion & Activation ===> Coagulation Cascade Activation           |
|                           (Target of Antiplatelets)             (Target of Anticoagulants)        |
|                                     ||                                    ||                      |
|                                     /                                     /                       |
|                             Primary Platelet Plug                 Fibrin Mesh Formation           |
+---------------------------------------------------------------------------------------------------+

Discontinuing antithrombotic therapy prior to dental procedures creates a hypercoagulable rebound state. The risk of mortality or permanent disability from a thromboembolic stroke far outweighs the risk of localized, manageable oral bleeding.

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Antiplatelet Therapies

Antiplatelet agents inhibit primary haemostasis by preventing platelet activation and aggregation.

Common Antiplatelet Medications

• Aspirin: Irreversibly inhibits COX-1, blocking synthesis of Thromboxane $A_2$ ($TXA_2$) for the lifespan of the platelet (~7-10 days).
• P2Y12 Receptor Antagonists (Clopidogrel, Prasugrel, Ticagrelor): Inhibit ADP-induced platelet activation.
• Dual Antiplatelet Therapy (DAPT): Combination of Aspirin plus a P2Y12 inhibitor (e.g., Aspirin + Clopidogrel), commonly prescribed for 6-12 months following acute coronary syndrome or coronary stent insertion.

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Vitamin K Antagonists (Warfarin)

Warfarin inhibits hepatic vitamin K epoxide reductase, blocking gamma-carboxylation of clotting factors II, VII, IX, and X, as well as proteins C and S.

International Normalised Ratio (INR) Protocol

Warfarin monitoring relies on the INR, a standardized measure of prothrombin time.

• Target Therapeutic Range: 2.0 to 3.0 for atrial fibrillation and DVT; 2.5 to 3.5 for mechanical heart valves.
• Pre-Operative INR Testing: INR should be measured within 24 hours prior to minor oral surgery (or up to 72 hours if the patient has a stable INR history).

INR CLINICAL THRESHOLDS FOR MINOR ORAL SURGERY:
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- INR <= 4.0: PROCEED with minor oral surgery WITHOUT altering Warfarin dose.
- INR > 4.0: DO NOT OPERATE. Refer to prescribing medical practitioner for dose adjustment.
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Minor Oral Surgery Definition: Extraction of 1 to 3 teeth, periodontal debridement,
minor soft tissue biopsy, or localized endodontic surgery.

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Direct Oral Anticoagulants (DOACs / NOACs)

DOACs directly target specific coagulation factors, featuring rapid onset (1-4 hours), predictable pharmacokinetics, short elimination half-lives (12-15 hours), and no requirement for routine INR monitoring.

Classification & Properties of DOACs

• Direct Thrombin (Factor IIa) Inhibitor: Dabigatran (Pradaxa).
• Direct Factor Xa Inhibitors: Rivaroxaban (Xarelto), Apixaban (Eliquis), Edoxaban (Lixiana).

Dental Management Protocol for DOACs

• Do NOT stop DOAC therapy for minor oral surgical procedures.
• Timing Optimization: Perform procedures at trough plasma drug concentration:
  • For once-daily DOACs (e.g., Rivaroxaban taken in evening): Schedule appointment in the morning.
  • For twice-daily DOACs (e.g., Apixaban/Dabigatran taken morning and evening): Perform surgery just before the morning dose, or instruct patient to delay morning dose until haemostasis is verified post-surgery.
• Schedule procedures early in the day and early in the week to allow management of any delayed oozing.

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Perioperative Surgical Protocols & Local Haemostatic Measures

When treating patients on antithrombotic therapy, surgical execution and local haemostasis are vital.

Step-by-Step Local Haemostasis Protocol

1. Atraumatic Surgical Technique: Minimise tissue trauma, reflect full-thickness mucoperiosteal flaps cleanly, and smooth sharp alveolar bone crests.
2. Socket Dressing / Pack: Place an intra-socket haemostatic agent such as Oxidized Regenerated Cellulose (Surgicel) or Resorbable Gelatin Sponge (Gelfoam).
3. Suturing: Place 3-0 or 4-0 resorbable interrupted or cross-mattress sutures across socket margins under tension to adapt tissue flaps firmly.
4. Tranexamic Acid (TXA) Local Application: An antifibrinolytic agent that competitively inhibits plasminogen activation.
   • Topical Application: Saturate a sterile gauze pad with 5% Tranexamic Acid solution (or crush a 500 mg tablet in water) and apply firm pressure over surgical site for 20 minutes.
   • Post-Op Rinse: Prescribe 4.8% Tranexamic Acid mouthwash (10 mL rinse for 2 minutes, 4 times daily for 2 to 5 days). Instruct patient not to swallow.
5. Post-Operative Instructions: Avoid rinsing vigorously for 24 hours, avoid drinking through straws, avoid hot fluids, avoid smoking, and avoid strenuous exercise.

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|                               LOCAL HAEMOSTATIC MEASURES MATRIX                                   |
|                                                                                                   |
|  1. Oxidized Cellulose / Gelatin Sponge in Socket                                                 |
|  2. Resorbable Sutures to approximate mucosal margins                                            |
|  3. Firm pressure with 5% Tranexamic Acid soaked gauze (20 min)                                   |
|  4. Post-op 4.8% Tranexamic Acid mouthwash (qid for 2-5 days)                                     |
+---------------------------------------------------------------------------------------------------+

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Management of Post-Extraction Haemorrhage

If persistent intraoral bleeding occurs post-operatively:

• Position patient upright, clear clots with suction, and identify exact source of bleeding (gingival margin vs intra-bony socket).
• Administer local anaesthetic containing 1:80,000 adrenaline directly adjacent to bleeding site.
• Debride excess fragile breakdown clot, repack socket with oxidized cellulose, resuture firmly, and re-apply pressure with Tranexamic Acid soaked gauze for 30 minutes.
• Re-check systemic vital signs and blood pressure. If bleeding remains uncontrollable despite local measures, arrange emergency medical transfer for systemic reversal or factor administration.