What is the recommended management for arterial thrombi versus venous thrombi in typical adult patients?

Management of Arterial vs Venous Thrombi

Arterial thrombi require antiplatelet therapy (aspirin or clopidogrel) as first-line treatment, whereas venous thrombi require anticoagulation with DOACs or LMWH as first-line treatment. 1, 2

Fundamental Pathophysiologic Distinction

• Arterial thrombi are platelet-rich "white clots" that form at sites of atherosclerotic plaque rupture under high shear stress conditions, making them responsive to antiplatelet agents 2, 3
• Venous thrombi are fibrin-rich "red clots" that develop in low-flow, low-shear environments and are mediated by the plasmatic coagulation cascade, requiring anticoagulation 2, 3

Arterial Thrombosis Management

Peripheral Arterial Disease & Chronic Limb Ischemia

• Aspirin 75-325 mg daily is recommended as lifelong first-line therapy for all patients with peripheral arterial occlusive disease, regardless of whether they have clinically manifest coronary or cerebrovascular disease 4
• Clopidogrel 75 mg daily is an alternative to aspirin, though aspirin should be used preferentially due to cost-effectiveness and equivalent efficacy 4
• Anticoagulation with warfarin or heparin is contraindicated in patients with intermittent claudication due to increased bleeding risk without thrombotic benefit 4

Acute Arterial Thrombosis or Embolism

• Immediate systemic anticoagulation with unfractionated heparin (UFH) is required for acute arterial emboli or thrombosis 4
• Following initial UFH, transition to long-term vitamin K antagonist (VKA) therapy in patients with arterial embolism 4
• For patients undergoing major vascular reconstructive procedures, administer UFH at the time of vascular cross-clamp application 4

Post-Revascularization Management

• After prosthetic infrainguinal bypass: aspirin indefinitely 4
• After infrainguinal femoropopliteal or distal vein bypass: aspirin alone is sufficient for routine patients 4
• For high-risk patients with bypass occlusion risk factors: consider VKA plus aspirin combination therapy 4

Venous Thromboembolism Management

Acute DVT or Pulmonary Embolism

• DOACs are the preferred first-line agents for symptomatic DVT or PE in adults 1, 5
  • Rivaroxaban: 15 mg twice daily for 21 days, then 20 mg once daily 1
  • Apixaban: 10 mg twice daily for 7 days, then 5 mg twice daily 1
• LMWH (enoxaparin 1 mg/kg subcutaneously every 12 hours) or fondaparinux are alternatives to DOACs and are preferred over unfractionated heparin 1

Iliofemoral DVT Specific Considerations

• Anticoagulation alone is the standard therapy for most iliofemoral DVT; catheter-directed thrombolysis (CDT) showed no reduction in post-thrombotic syndrome at 2 years in the ATTRACT trial 1
• CDT is reserved for select patients who are <65 years old, have acute (<14 days) symptoms, severe limb-threatening ischemia (phlegmasia cerulea dolens), low bleeding risk, and good functional status 1
• Systemic thrombolysis is contraindicated due to 14% major bleeding risk; if thrombolysis is needed, use low-dose catheter-directed rtPA (≈0.01 mg/kg) 6, 1

Duration of Anticoagulation

• Provoked DVT (surgery, transient risk factor): fixed 3-month course is sufficient 1, 5
• Unprovoked DVT: minimum 3 months, then indefinite therapy if bleeding risk is low-to-moderate (annual recurrence risk >5% if stopped) 1, 5
• Cancer-associated DVT: extend anticoagulation for at least 3-6 months and continue while cancer is active; LMWH is preferred over DOACs or warfarin 1

Extended Therapy Options

• Standard-dose DOAC (same dose as initial treatment) is preferred for extended therapy 5
• Reduced-dose DOAC (rivaroxaban 10 mg once daily or apixaban 2.5 mg twice daily) is an alternative to minimize bleeding risk while maintaining efficacy 5

Pediatric Considerations

Venous Thromboembolism in Children

• Anticoagulation is recommended for symptomatic DVT or PE in pediatric patients, based on extrapolation from adult data and the life-threatening nature of VTE in sick hospitalized children 6
• For submassive PE (right ventricular dysfunction without hemodynamic compromise): use anticoagulation alone rather than thrombolysis 6
• For massive PE (with hemodynamic compromise): consider thrombolysis followed by anticoagulation 6

Cerebral Sinovenous Thrombosis (CSVT)

• Anticoagulation is recommended for pediatric CSVT even in the presence of hemorrhage secondary to venous congestion, with reduced mortality (RR 0.12) and improved thrombus resolution 6

Special Circumstances Requiring Both Antiplatelet and Anticoagulation

Antiphospholipid Syndrome

• Patients with antiphospholipid syndrome may develop both arterial and venous thromboses and require individualized assessment of whether anticoagulation, antiplatelet therapy, or both are needed 2, 7

Coronary Artery Disease with Concurrent VTE

• Patients with acute myocardial infarction or coronary stenting who also have VTE may require dual antiplatelet therapy plus anticoagulation (triple therapy), though this significantly increases bleeding risk 2

IVC Filter Considerations

• IVC filters are contraindicated for routine use in patients who can receive anticoagulation; although filters reduce symptomatic PE (6.2% vs 15.1% at 8 years), they increase recurrent DVT and do not improve mortality 6, 1
• Place IVC filters only when absolute contraindication to anticoagulation exists or active bleeding is present 1
• Resume anticoagulation once the contraindication resolves 1

Critical Pitfalls to Avoid

• Do not use anticoagulation for chronic peripheral arterial disease or intermittent claudication—this increases bleeding without benefit 4
• Do not use antiplatelet therapy alone for acute DVT or PE—this is inadequate for venous thrombosis 1
• Do not delay anticoagulation while awaiting imaging in patients with high clinical suspicion of VTE; start empiric parenteral anticoagulation promptly 1
• Do not use systemic thrombolysis for DVT; transfer to centers capable of catheter-directed therapy if thrombolysis is indicated 6, 1
• Do not discontinue anticoagulation prematurely after unprovoked DVT, as this markedly increases recurrence risk 1, 5
• Do not restart anticoagulation in elderly patients with prior major bleeding at a critical site unless the bleeding source has been identified and corrected 8