Venous Thromboembolism

Matthew Everett

Background 

  • Includes DVTs and PE. See “Pulmonary Embolism” section in cardiology.
  • Virchow’s triad: stasis, vessel wall injury and hypercoagulability.
  • Risk factors for provoked DVT/PE.
    • Major risk factors: major surgery, trauma or fracture, active cancer (Pancreatic, brain, lung, ovarian, and metastatic cancers are highest risk), prior VTE, prolonged immobility such as hospitalization >3 days or SCI, inherited hypercoagulability, pregnancy and postpartum period (first 6 weeks).
    • Minor Risk Factors: older age, obesity, hormone therapy, smoking, minor surgery.
  • Non-transient risk factors: malignancy (active), myeloproliferative disorders, IBD, liver disease, COPD, CHF, CKD, hereditary thrombophilia (factor V Leiden and prothrombin gene mutations most common), antiphospholipid syndrome, prior VTE.

Evaluation 

  • Asymmetric calf swelling of >2cm sensitivity and specificity for DVT of 60-70%.
  • Classic triad of PE: SOB, pleuritic chest pain and coughing +/- hemoptysis.
  • Wells’ Criteria for DVT can help guide diagnostic testing.
    • If a pt has a low pre-test probability, a negative D-dimer can rule out DVT.
    • In a high pre-test probability pt a negative D-dimer is less helpful.
  • Whole-leg ultrasounds with doppler is gold standard for DVT
  • CT pulmonary angiography is gold standard for PE (lesser alternative V/Q scan).

Management 

  • Prophylaxis: Padua score risk assessment
    • Score > 4 high risk: Pharmacologic prophylaxis (daily SC enoxaparin 40 mg or TID SC heparin)
    • Score <4 is low risk; recommend ambulation and SCDs.
  • If contraindications (active bleeding, thrombocytopenia) recommend ambulation and SCDs.
  • Treatment (see anticoagulation section).
  • Heparins: UFH or LMWH.
  • DOACs: Rivaroxaban or apixaban can be first-line (no heparin bridge needed).
  • Warfarin: Bridge with therapeutic UFH/LMWH (5+ days) until INR is 2-3.
  • See “Pulmonary Embolism” section in cardiology for interventions on PE.
  • Duration of treatment:
    • Provoked: 3-6 months provided the provoking factor (trauma, surgery) has resolved.
    • Unprovoked (e.g., cancer, genetic defects): typically requires life-long anticoagulation along with assistance from hematology.

Complications 

  • Post-Thrombotic Syndrome: Chronic leg pain, swelling, ulcers from vein damage (20-50% of DVT cases). Compression stockings reduce risk.
  • Chronic Thromboembolic Pulmonary Hypertension (CTEPH): Rare, from unresolved PE causing lung artery pressure buildup, leading to Group 4 pulmonary HTN.

Anticoagulation in malignancy 

  • Treatment of established VTE (ASCO 2021): LMWH or DOACs (apixaban, rivaroxaban, edoxaban). Avoid DOACs in GI/GU cancers due to bleeding risk. Hold anticoagulation and consult NSGY if brain mets.
  • Primary Prophylaxis
  • Khorana Score: Predicts VTE risk in outpatients on chemo.
  • Apixaban 2.5 mg BID, rivaroxaban 10 mg daily, or LMWH for high-risk outpatients (e.g., pancreatic cancer, Khorana ≥2).

Additional Information 

  • Should we get a follow up ultrasound?
    • Typically, it is unnecessary for provoked DVT with clear resolution and lack of symptoms.
    • Recommended or considered for unprovoked DVT, no clear trigger, non-transient risk factors (e.g., factor V Leiden, cancer). F/u ultrasound can:
      • Assess residual clot to guide whether to extend AC
      • Assess persistent residual vein occlusion which doubles recurrence risk.
  • What about IVC filters?
    • Select circumstances for these: In pts with acute DVT or PE and in whom anti-coagulation failed or absolutely contraindicated (thrombocytopenia, recent intra-cranial bleed, recent GI bleed).
    • Placement of a retrievable IVC filter should be discussed with Hematology and IR.
    • Complications of IVC filters include filter thrombosis, migration/fracture, perforation and retrieval issues (PREPIC trials (1998, 2005, 2015) showed filters reduce PE risk short-term but increase DVT recurrence long-term, with no mortality benefit).
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