What is the recommended treatment for thrombolysis in patients with massive or submassive pulmonary embolism?

Thrombolysis in Pulmonary Embolism

Thrombolytic therapy is indicated for patients with massive pulmonary embolism (PE) presenting with shock and/or hypotension, and should be administered as 100 mg of alteplase over 2 hours intravenously. 1, 2, 3

Definition and Classification of PE

• Massive PE: Defined as PE with shock and/or hypotension (systolic blood pressure <90 mmHg for at least 15 minutes or requiring inotropic support) 1, 3
• Submassive PE: Defined as PE with evidence of right ventricular (RV) dysfunction without hypotension 1

Treatment Algorithm for Massive PE

1. First-line therapy: Administer alteplase 100 mg over 2 hours via peripheral intravenous catheter 1, 2, 3

   • Alternative regimen: 0.6 mg/kg alteplase bolus over 15 minutes (maximum 50 mg) 1, 3, 4
   • For cardiac arrest or rapidly deteriorating patients: 50 mg alteplase as IV bolus 2, 3

2. Anticoagulation management:

   • Withhold heparin during the 2-hour alteplase infusion 2
   • Resume heparin (1280 IU/hour continuous infusion) after alteplase when APTT is less than twice the upper limit of normal 1, 3

3. If thrombolysis fails:

   • Consider catheter-based interventions (aspiration thrombectomy, thrombus fragmentation, or rheolytic thrombectomy) 1
   • Consider surgical embolectomy if patient fails to respond to thrombolysis within the first hour or if thrombolysis is contraindicated 1

Treatment Considerations for Submassive PE

• Thrombolysis may be considered for patients with submassive PE who have RV dysfunction on echocardiography, elevated cardiac biomarkers (troponin, BNP), and no contraindications to fibrinolysis 1, 5
• The benefit of thrombolysis in submassive PE is less clear than in massive PE, but it can prevent clinical deterioration requiring escalation of treatment 5

Contraindications to Thrombolysis

• Absolute contraindications: Recent hemorrhage, stroke, current gastrointestinal hemorrhage 1
• Relative contraindications: Peptic ulcer disease, surgery within preceding seven days, prolonged cardiorespiratory resuscitation 1
• Most contraindications are considered relative in the setting of life-threatening massive PE 1, 3

Diagnostic Confirmation Before Thrombolysis

• It is preferable to confirm PE diagnosis with imaging (CTPA, V/Q scan) before initiating thrombolysis 1, 3
• When imaging is unavailable or unsafe due to patient instability, thrombolysis may be considered based on high clinical suspicion and evidence of RV dysfunction on bedside echocardiography 1, 2

Monitoring and Outcomes

• Monitor for clinical improvement and hemodynamic parameters (pulmonary artery pressure, cardiac index) 3, 6
• Expect improvement in hemodynamic parameters within 1-2 hours after thrombolysis 6, 7
• Major bleeding occurs in approximately 11-24% of patients depending on the regimen 3, 7

Special Considerations

• In pregnancy, thrombolysis may be appropriate for massive PE but should be avoided within six hours of delivery or in the early postpartum period due to high bleeding risk 1
• Consider inferior vena caval (IVC) filters for patients at high risk of further emboli in whom anticoagulation is contraindicated or in those with recurrent embolism despite adequate anticoagulation 1