Venous Thromboembolism
Sarah Fittro
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 o Score > 4 high risk, VTE risk ~11% over 90 days without prophylaxis. Recommend pharmacologic prophylaxis (enoxaparin 40 mg SC daily or ppx dose heparin)
- Score <4 is low risk; recommend ambulation and SCDs
- Treatment (see anticoagulation section)
- Heparins: UFH or LMWH, e.g., enoxaparin starts immediately.
- DOACs: Rivaroxaban or apixaban can be first-line (no heparin bridge needed).
- Warfarin: Started with UFH/LMWH overlap (5+ days) until INR is 2-3, then heparin stops.
- Severe PE:
- Thrombolytics (e.g., alteplase) for massive PE with hemodynamic instability
- Embolectomy (surgical or catheter-based) if thrombolysis fails.
- Duration of treatment
- Provoked: 3-6 months or until provoking factor (trauma, surgery) is 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 of this.
- Chronic Thromboembolic Pulmonary Hypertension (CTEPH): Rare, from unresolved PE causing lung artery pressure buildup.
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.
- Primary Prophylaxis o 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?
- When it’s typically not needed: provoked DVT with clear resolution: If DVT was triggered by transient risk and symptoms resolve, follow-up imaging isn’t routine.
- When it’s recommended or considered: unprovoked DVT with no clear trigger suggests underlying risk (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 anticoagulation is absolutely contraindicated (thrombocytopenia, recent intra-cranial bleed, recent GI bleed) or recurrent PE despite adequate AC
- 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) showed filters reduce PE risk short-term but increase DVT recurrence long-term, with no mortality benefit)
