What are the indications for mechanical thrombectomy in patients with pulmonary embolism (PE)?

Indications for Mechanical Thrombectomy in Pulmonary Embolism

Mechanical thrombectomy is primarily indicated for patients with massive pulmonary embolism who have contraindications to fibrinolytic therapy or who remain hemodynamically unstable despite fibrinolytic treatment. 1

Primary Indications

• Massive PE with contraindications to fibrinolytic therapy - Patients with hemodynamic instability (systolic BP <90 mmHg for at least 15 minutes or requiring inotropic support) who cannot receive thrombolytics 1, 2
• Massive PE with failed thrombolytic therapy - Patients who remain unstable after receiving fibrinolysis 1, 2
• High-risk PE requiring transfer - Patients with massive PE who cannot receive fibrinolysis at centers without catheter or surgical embolectomy capabilities should be transferred to centers with these services 1

Secondary Indications

• Submassive PE with adverse prognosis - May be considered for patients with submassive PE showing clinical evidence of deterioration, including:
  • New hemodynamic instability 1
  • Worsening respiratory failure 1
  • Severe right ventricular dysfunction 1
  • Major myocardial necrosis 1

Contraindications

• Low-risk PE - Mechanical thrombectomy is not recommended for patients with low-risk PE 1, 2
• Stable submassive PE with minor RV dysfunction - Not recommended for patients with submassive PE who have minor RV dysfunction, minor myocardial necrosis, and no clinical worsening 1

Technical Considerations

• Operator experience - Only operators experienced with these techniques should perform catheter-based interventions 1
• Procedural expertise - Interventionalists must be comfortable managing cardiogenic shock, bradyarrhythmias, anticoagulation, and cardiac tamponade 1
• Monitoring - Invasive arterial access is recommended for patients with shock or hypotension to help guide vasopressor management 1

Procedural Approach

• Catheter selection - Typically uses a 6F femoral venous sheath with a 6F angled pigtail catheter advanced into each main pulmonary artery 1
• Anticoagulation during procedure - Either unfractionated heparin (70 IU/kg IV bolus) or bivalirudin (0.75 mg/kg IV bolus, then 1.75 mg/kg/h) should be used 1
• Conservative approach - Early termination of the procedure once hemodynamic and clinical parameters improve may be associated with lower complication rates 3

Outcomes and Efficacy

• Hemodynamic improvement - Studies show significant improvements in mean pulmonary artery pressure after mechanical thrombectomy 4, 5
• Respiratory parameters - Significant improvements in PaO2/FiO2 ratio have been observed after the procedure 6
• Mortality benefit - In-hospital mortality rates of 15-32% have been reported in high-risk patients treated with mechanical thrombectomy 3, 5

Multidisciplinary Approach

• Pulmonary Embolism Response Team (PERT) - For complex cases, especially intermediate-high risk PE, involvement of a multidisciplinary PERT is encouraged 2
• Transfer protocols - Institutions should have plans in place for expedited transfer of patients requiring mechanical thrombectomy 1

Pitfalls and Caveats

• Avoid in stable patients - Mechanical thrombectomy has not shown a favorable risk-benefit profile in hemodynamically stable patients with submassive PE 1, 2
• Procedural complications - Though rare, complications can include pulmonary artery rupture 6
• Temporary pacemaker - May be required during rheolytic thrombectomy due to risk of bradyarrhythmias 1
• IVC filters - Consider IVC filter placement if anticoagulation treatment is not possible within 1 month of symptomatic VTE onset 1