VTE / PE

Symptoms

• Patients with PE have few symptoms, and many non-specific and non-sensitive.
• General Symptoms:
  • Tachypnea (90%)
  • Chest or pleuritic pain (85%)
  • Dyspnea (84%)
  • Anxiety, crackles, cough.
  • Likelihood of PE is lower if does not have dyspnea or tachycardia.

Pre-Test Probability 

• Signs an symptoms are non-sensitive and non-specific
• Several diagnostic Risk Scores have been developed to decrease need for imaging.

• Here are some prediction scoring systems:

• Revised Geneva Scoring System

• PERC rule: (Pulmonary Embolism Rule Out Criteria)
• Used mostly used by ER physicians (for VERY LOW pre-test probability)

• 1. Age <50 2. HR <100 3. O2 sat >94% on RA 4. No Hx of DVT/PE 5. No recent surgery 6. No hemoptysis 7. No estrogen replacement 8. No clinical signs of DVT If all are negative: <2% chance of PE Can use only if DO NOT suspect PE

• Use of D-Dimer in patients with suspected PE/DVT will save 30% of pts from further investigations.
  • D-Dimer not recommended for moderate to high risk of PE or in hospitalized patients.
  • Use only if LOW pre-test probability (if high risk of PE, D-dimer does not change pretest as much)

Initial Investigations / D-Dimer

• ECG, CXR to rule out other causes (Pneumonia, ACS)
  • ECG in PE:
    • Most common: sinus tachycardia.
    • R-sided heart strain: (most aren't large enough to cause R-heart strain)
      • S1Q3T3 (only seen in minority of patients)
      • R-axis devation and RBBB
      • Large R-atrium.
  • CXR: Hampton's Hump (wedge shape density in the periphery due to infarction) or Westermark sign (darker area of reduced perfusion)
• 
  • Hampton's Hump                                                    Westermark's sign

• D-Dimer:
  • Use of D-Dimer in patients with suspected PE/DVT will save 30% of pts from further investigations.
    • D-Dimer not recommended for moderate to high risk of PE or in hospitalized patients.
    • Use only if LOW pre-test probability (if high risk of PE, D-dimer does not change pretest as much)
  • Negative Predictive Value = 94%
    • D-Dimer is NOT useful when POSITIVE (poor specificity), only useful if negative.
    • In pregnant patients D-dimer levels increase, but still useful in first trimester as at least 50% will normally have a negative D-dimer, which safely excludes TE.
      • In 2nd trimester 75% will be positive, and in 3rd trimester nearly all are positive.  If positive may need a low-dose perfusion scan or V/Q scan, consult radiology.

Definitive PE Studies

• CT angio (Sn + Sp >90%)
  • Primary method of diagnosis of PE due to high Sn and Sp.
  • Advantages:
    • May provide other diagnostic clues.
    • Preferred if baseline CXR abnormal (VQ scan difficult to interpret)
  • Disadvantages:
    • High radiation exposure
    • More challenging in obese people (hard to time contrast to pulmonary vasculature).  May need an open scanner.
• V/Q scan  (Sn 50-98%, Sp 20-60%)
  • VQ scan is an option if CT angiography not available or contraindicated.
  • Advantages:
    • Low radiation dose.
    • No contrast dye.
    • Useful with normal cardiopulmonary status at baseline.
    • Preferred for chronic PEs with multiple lobar perfusion defects w/o anatomic matching ventilation abnormalities.  
    • Normal results practically exclude PE in setting of high pretest probability.
  • Diasadvantages:
    • Unreliable if structural lung disease (COPD, etc..) or if holding breath is difficult.
    • VQ interpretation dependent on pre-test likelihood.
• Gold Standard: Conventional pulmonary angiography with digital subtraction
  • Invasive: only reserved for patients if uncertainty remains after CT angiography.
  • OR if direct measurement of hemodynamics is needed.

DVT Studies in PE

• If unable to get chest imaging to exclude PE, it may be worthwhile to perform a compression ultrasound of legs.
  • 90% of clots start in legs.
  • If positive leg venous ultrasound --> will treat for DVT and presumed PE (treatment similar)
• If no DVT is found: may need chest imaging.
• If PE is found on chest imaging --> Leg USS is not indicated (will not change management)

Other Investigations

• Echocardiography
  • For select patients with suspected or confirmed PE who are too unstable for CTA or VQ scanning.
  • Findings:
    • Elevated PA systolic pressure.
    • RV dilation / hypokinesis
    • Paradoxical septal motion
    • Diminished LV size.
    • **McConnel Sign**

Stable

• Achieve anticoagulation within 24hrs to prevent progression and recurrence of clot.
  • Allow time for natural lysis of existing clot (days to weeks).
  • Acutely use: UFH, LMWH, and rarely Fondaparinux (pentasaccharide)
    • New oral medications (rivaroxaban, dabigatran etc..) possible but less experience.
  • If anticoagulation (active internal bleed, hemorrhagic stroke, coagulopathy, remote GI bleed, brain mets).  Must weigh risks--benefits. 
  • Can start warfarin right away, but do not bolus (initially hypercoagulable), and continue LMWH/UFH for 4-5 days until reach target INR levels and >2 days of stable INR. (2 days overlap) to ensure reliable anticoagulation.
• Big controversy whether thrombolytics should be used for stable patients but RV strain on CT or Echo.
  • Dilation, decreased RV systolic function.
  • Can look at biomarkers (troponin, BNP levels)
  • Area of active research, no definitive answer.

Unstable

• These are patients that have high mortality rate, and may require thrombolysis.
• They are hemodynamically unstable patients have high risk of death:
  • NO TIME to wait for natural clot resorption --> Thrombolytic therapy, followed by anticoagulation.
  • Other options:
    • Catheter embolectomy or surgical embolectomy.
• Defined as refractory hypotension
  • Very high pulmonary vascular resistance and high pulmonary pressure.  Drop in cardiac output. 
  • May need mechanical ventilation.
  • Give VOLUME --> fluid rescucitation to improve preload to RV.
    • However too much fluid can overload the RV (can cause ischemia of RV).
• Contraindications for thrombolytic therapy:

  • Contraindications to Thrombolytic Therapy

    Absolute History of intracranial bleeding CVA within the past 3mo (ischemic CVA within the past 3 hours) Closed head or facial trauma within the past 3 mo Suspected aortic dissection Active internal bleeding Uncontrolled hypertension (sBP > 180, dBP > 100) Relative Current anticoagulation or bleeding diathesis Surgery or invasive procedures in the past 2 weeks Prolonged CPR ≥ 10min Controlled severe HTN Diabetic or hemorrhagic retinopathy Pregnancy   Risks of thrombolysis: - 2.1% risk of ICH - 1.6% risk of fatal non-ICH hemorrhage.

Long-Term Management

• In acute PE, pts are at a substantial risk of recurrence (esp in first 1 month)
• Continue anticoagulation for at least 3 months.
• Standard therapy:
  • Warfarin (INR 2-3)
  • NEW: Rivaroxaban
• How long to continue?
  • 3 months of anticoagulation for everyone, after that:
    • Can stop if known predisposing factor that is resolved.
    • Continue as long as predisposing factor present (surgery, immobility)
    • Consider indefinitely if:
      • predisposing factor continuous (cancer).
      • History of proximal DVT
      • Idiopathic  (aka "unprovoked") VTE
  • Some perform D-Dimer 2 weeks before stopping anticoagulation and also check 2-weeks after stopping.
    • If positive, then four-fold risk of recurrent PE than normal D-Dimer.
    • Helps risk-stratify, if D-Dimer positive --> consider continuing.
• NOTE: For patients requiring long-term oral anticoagulants, role of NOACs is uncertain.

IVC Filters

• Indications:
  • If not candidate for acute or chronic anticoagulation.
  • Clotting despite anticoagulation
  • High risk of recurrent emboli
  • Low cardiopulmonary reserve (such as pulmonary HTN) - even if on anticoagulation.
• Placed into IVC below renal veins.
• Prevent any DVTs that embolize.
• Disadvantages:
  • Higher risk of lower-limb DVT with filter in-situ.
  • Filter can migrate (even into RV)
  • Filter can endothelialize if not removed after few months (will be impossible to safely remove)
  • Clot can form on filter, above filter, or around the filter. (Can cause chronic pain)
  • Can get venous collateralization around the filter, and emboli can bypass.
• Preferrable to continue anticoagulation after filter installed.
• MOST (80-90%) are never removed and forgotten.  DO NOT forget to remove if not needed.