How to manage a hemodynamically stable patient with bilateral pulmonary embolism (PE) and a saddle embolus?

Management of Hemodynamically Stable Bilateral PE with Saddle Embolus

For hemodynamically stable patients with bilateral pulmonary embolism (PE) and saddle embolus, therapeutic anticoagulation alone is the recommended first-line treatment, with close monitoring for clinical deterioration.

Initial Assessment and Risk Stratification

When managing a patient with bilateral PE and saddle embolus who is hemodynamically stable, the following approach is recommended:

1. Confirm hemodynamic stability:

   • Stable systolic blood pressure (≥90 mmHg)
   • No signs of obstructive shock
   • No need for inotropic support

2. Assess for right ventricular (RV) dysfunction:

   • Obtain echocardiography to evaluate RV size and function
   • Measure cardiac biomarkers (troponin, NT-proBNP)
   • Calculate PE severity index (PESI) score

3. Laboratory evaluation:

   • Complete blood count with platelet count
   • PT, aPTT
   • Liver and kidney function tests
   • Cardiac biomarkers (troponin, NT-proBNP)
   • ECG

Treatment Algorithm

Step 1: Immediate Anticoagulation

Begin therapeutic anticoagulation immediately 1:

• LMWH (preferred): Enoxaparin 1 mg/kg twice daily or 1.5 mg/kg once daily 2
• Unfractionated heparin (UFH): Consider for patients who may need rapid reversal or have severe renal impairment - 80 U/kg bolus followed by 18 U/kg/hour infusion, adjusted based on aPTT 1
• Direct oral anticoagulants (DOACs): Can be started immediately without parenteral anticoagulation lead-in
  • Apixaban: 10 mg BID for 7 days, then 5 mg BID
  • Rivaroxaban: 15 mg BID for 21 days, then 20 mg daily

Step 2: Monitor for Clinical Deterioration

Despite the presence of a saddle embolus, which appears ominous on imaging, most hemodynamically stable patients respond well to standard anticoagulation 3. However, close monitoring is essential:

• Continuous assessment of vital signs
• Serial evaluation of RV function if initially abnormal
• Monitor for signs of clinical deterioration (increasing oxygen requirements, worsening tachycardia, hypotension)

Step 3: Consider Advanced Interventions if Deterioration Occurs

If the patient deteriorates despite anticoagulation, consider rescue interventions 4:

• Systemic thrombolysis: For patients who develop hemodynamic instability
• Catheter-directed interventions: Consider for patients with contraindications to systemic thrombolysis or those who fail thrombolysis

Special Considerations

1. Saddle embolus appearance alone does not necessitate thrombolysis:

   • Studies show that most patients with saddle PE who are hemodynamically stable have good outcomes with standard anticoagulation alone 5, 3
   • The 2-week mortality for saddle PE is approximately 5.8%, but this varies based on hemodynamic status and RV function 5

2. Role of Pulmonary Embolism Response Team (PERT):

   • Consider PERT activation for multidisciplinary decision-making in complex cases 1
   • Particularly valuable for intermediate-high risk patients

3. Duration of anticoagulation 1:

   • Minimum 3 months for provoked PE
   • Extended (>3 months) for unprovoked PE or persistent risk factors
   • Indefinite for recurrent PE

Common Pitfalls to Avoid

1. Overtreatment based solely on imaging appearance:

   • The term "saddle embolus" often creates alarm, but hemodynamic status and RV function are more important prognostic factors than clot location 3
   • Avoid unnecessary thrombolysis in stable patients without evidence of RV dysfunction

2. Underestimating deterioration risk:

   • Despite initial stability, some patients may deteriorate rapidly
   • Maintain vigilant monitoring, especially in the first 24-48 hours

3. Delayed anticoagulation:

   • Begin therapeutic anticoagulation immediately upon diagnosis
   • Do not wait for additional testing before initiating treatment

4. Inadequate follow-up:

   • Arrange follow-up at 3-6 months to assess for chronic thromboembolic pulmonary hypertension 1
   • Evaluate for underlying causes of PE to guide duration of anticoagulation

The American Society of Hematology guidelines strongly recommend against routine use of thrombolysis for hemodynamically stable patients with PE, even those with RV dysfunction (submassive PE) 4. This recommendation is supported by evidence showing that anticoagulation alone is generally sufficient for these patients, with thrombolysis reserved for those who develop hemodynamic instability.