What is the management of pulmonary embolism in an adult patient with no known allergies or contraindications?

Management of Pulmonary Embolism

Initiate anticoagulation immediately without delay in all patients with suspected PE who have intermediate or high clinical probability, even while diagnostic workup is in progress. 1, 2

Immediate Risk Stratification

The first critical step is determining hemodynamic stability, as this dictates the entire treatment pathway and mortality risk 2, 3:

• High-risk (massive) PE: Sustained hypotension (systolic BP <90 mmHg for ≥15 minutes), cardiogenic shock, or cardiac arrest 1
• Intermediate-risk (submassive) PE: Hemodynamically stable but with evidence of right ventricular dysfunction or myocardial injury 1
• Low-risk PE: Hemodynamically stable without RV dysfunction 1

Perform bedside echocardiography immediately in unstable patients to differentiate high-risk PE from cardiac tamponade or acute MI 2.

High-Risk PE Management

Systemic thrombolytic therapy is the first-line treatment for high-risk PE presenting with cardiogenic shock or persistent hypotension. 1, 3

Thrombolysis Protocol

• Alteplase 100 mg IV over 2 hours is the standard regimen for stable high-risk patients 1, 3, 4
• Alteplase 50 mg IV bolus immediately for cardiac arrest or imminent collapse 2, 3
• Begin CPR immediately if cardiac arrest occurs and administer the 50 mg bolus during resuscitation 3
• Initiate unfractionated heparin (UFH) with weight-adjusted bolus before or concurrent with thrombolysis 1, 5
• Resume UFH infusion 3 hours after thrombolysis completion 3

Alternative Interventions

If thrombolysis is contraindicated or fails 1:

• Surgical pulmonary embolectomy is recommended (Class I) 1
• Percutaneous catheter-directed treatment should be considered (Class IIa) 1
• ECMO may be considered in combination with surgical or catheter-directed treatment for refractory circulatory collapse 1

Critical Caveat for High-Risk PE

In immediately life-threatening PE, absolute contraindications to thrombolysis (such as recent surgery within 3 weeks or GI bleeding within the last month) become relative contraindications, as mortality benefit outweighs bleeding risk. 1, 3

Intermediate- and Low-Risk PE Management

Anticoagulation Selection

When initiating parenteral anticoagulation, LMWH or fondaparinux is recommended over UFH for most hemodynamically stable patients. 1, 2

When starting oral anticoagulation, a NOAC (apixaban, dabigatran, edoxaban, or rivaroxaban) is recommended in preference to a VKA. 1

Specific Anticoagulation Regimens

For parenteral therapy 1, 2:

• LMWH: Weight-based dosing (e.g., enoxaparin 1 mg/kg subcutaneously every 12 hours)
• Fondaparinux: Weight-based dosing subcutaneously once daily
• UFH: Reserved for patients requiring rapid reversal or with severe renal impairment; 80 units/kg IV bolus followed by 18 units/kg/hour infusion 2, 5

For oral therapy 1, 6:

• Rivaroxaban or apixaban: Can be started immediately without parenteral lead-in
• Dabigatran or edoxaban: Require 5-10 days of parenteral anticoagulation before transition
• VKA (warfarin): Overlap with parenteral anticoagulation until INR 2.0-3.0 (target 2.5) is achieved

When NOT to Use Thrombolysis

Do not routinely administer systemic thrombolysis as primary treatment in patients with intermediate- or low-risk PE. 1

However, rescue thrombolytic therapy should be administered if hemodynamic deterioration occurs despite anticoagulation 1.

Diagnostic Algorithm for Stable Patients

While anticoagulation is initiated 1, 2:

1. Assess clinical probability using Wells' criteria or Revised Geneva score 2
2. D-dimer testing: Only in low or intermediate probability patients; do NOT order in high probability patients as negative result does not safely exclude PE 1, 2
3. CT pulmonary angiography (CTPA): First-line imaging modality 2
   • Timing: Within 1 hour for massive PE, within 24 hours for non-massive PE 2
   • A normal CTPA in low/intermediate probability patients excludes PE without further testing 1
4. Compression ultrasound (CUS): If shows proximal DVT in patient with suspected PE, accept diagnosis of VTE and treat accordingly 1

Special Considerations

Vena Cava Filters

Do not routinely use inferior vena cava filters. 1

Potential indications are limited to 1:

• Absolute contraindication to anticoagulation
• Recurrent PE despite adequate anticoagulation
• High-risk VTE prophylaxis in select cases

Multidisciplinary PE Response Teams (PERT)

Set-up of PERTs is encouraged for management of high-risk and selected intermediate-risk PE cases, bringing together specialists from cardiology, pulmonology, interventional radiology, cardiac surgery, and intensive care to formulate real-time treatment plans 1.

Duration of Anticoagulation

• Minimum 3 months for all patients with PE 1, 6, 7
• Discontinue after 3 months if first PE secondary to major transient/reversible risk factor 1
• Indefinite anticoagulation for recurrent VTE not related to transient risk factors 1, 7
• Reassess regularly for drug tolerance, adherence, hepatic/renal function, and bleeding risk 1

Critical Pitfalls to Avoid

• Never delay anticoagulation waiting for imaging in intermediate/high probability patients, as PE mortality is 7% within 1 week even with treatment 2
• Do not transfer unstable patients for additional imaging; treat based on clinical grounds if cardiac arrest is imminent 2
• Do not use NOACs in severe renal impairment or antiphospholipid antibody syndrome 1
• Do not measure D-dimers in high clinical probability patients 1, 2
• Avoid therapeutic LMWH within 24 hours before thrombolysis due to significantly increased major bleeding risk 2