What is the recommended acute treatment for a patient with massive pulmonary embolism presenting with sustained systemic hypotension (systolic <90 mm Hg), shock, or cardiac arrest?

Massive Pulmonary Embolism: Acute Treatment

For massive pulmonary embolism with sustained hypotension (systolic <90 mmHg), shock, or cardiac arrest, systemic thrombolytic therapy with alteplase 100 mg IV over 2 hours is the first-line treatment, with surgical embolectomy reserved for patients with absolute contraindications to thrombolysis or those who fail thrombolytic therapy. 1, 2

Immediate Stabilization and Anticoagulation

• Start unfractionated heparin (UFH) immediately upon diagnosis unless active bleeding or absolute contraindications exist 3
• UFH is preferred over low molecular weight heparin in hemodynamically unstable patients because it allows rapid reversal and provides more predictable pharmacokinetics 3
• Withhold heparin during the 2-hour alteplase infusion, then resume therapeutic anticoagulation after completion 2

Thrombolytic Therapy Protocol

Standard dosing: Alteplase 100 mg as a continuous IV infusion over 2 hours via peripheral IV catheter 2

For cardiac arrest or rapidly deteriorating patients: Consider alteplase 50 mg as immediate IV bolus, with reassessment at 30 minutes 2

Indications for Thrombolysis

The mortality benefit is clearly established for massive PE defined as: 1, 4

• Sustained hypotension (SBP <90 mmHg for ≥15 minutes)
• Requiring inotropic support (not due to arrhythmia, hypovolemia, or sepsis)
• Pulselessness
• Persistent profound bradycardia (HR <40 bpm with shock signs)

Contraindications

• In life-threatening massive PE, most contraindications are relative given the 52.4% 90-day mortality without treatment 1
• The 25% in-hospital mortality for cardiogenic shock and 65% mortality for those requiring CPR justifies aggressive intervention despite bleeding risk 1, 4
• Major bleeding occurs in approximately 15% of patients receiving thrombolysis 3

Diagnostic Confirmation

• Imaging confirmation is preferred before thrombolysis, but do not delay treatment if the patient is too unstable for CT 2
• High clinical suspicion plus RV dysfunction on bedside echocardiography is sufficient to proceed with thrombolysis in unstable patients 2
• Proximal obstruction on CT, diagnostic perfusion scan with high clinical probability, or acute cor pulmonale on echo with high clinical suspicion all provide adequate diagnostic certainty 1

Surgical Embolectomy

Indications: 1, 3

• Absolute contraindications to thrombolysis
• Failed thrombolytic therapy with persistent shock
• Patients in cardiogenic shock who cannot wait for thrombolysis to take effect

Technique: Median sternotomy with normothermic cardiopulmonary bypass, avoiding aortic cross-clamping, with embolectomy via longitudinal pulmonary artery incision 1

Optimal candidates: Patients with subtotal obstruction of main pulmonary artery or major branches without fixed pulmonary hypertension 1

Extracorporeal Membrane Oxygenation (ECMO)

Consider veno-arterial ECMO as: 5, 6, 7

• Bridge to definitive interventional therapy in patients with cardiac arrest
• Supportive therapy when thrombolysis cannot unload the RV fast enough
• Rescue strategy for prolonged cardiac arrest from massive PE

Important caveat: ECMO use in massive PE shows lower mortality in registry reviews but no significant difference in meta-analyses due to study heterogeneity 5. ECMO carries substantial morbidity including systemic inflammatory response, hemorrhagic stroke, renal dysfunction, and bleeding 5

Critical Pitfalls to Avoid

• Do not use direct oral anticoagulants (DOACs) acutely in hemodynamically unstable PE—rivaroxaban is specifically not recommended as an alternative to UFH in patients who may require thrombolysis or pulmonary embolectomy 8
• Do not perform pulmonary angiography before thrombolysis in unstable patients—it is time-consuming, hazardous, and increases bleeding complications 1
• Do not wait for angiographic confirmation in deteriorating patients—bedside echo showing RV dysfunction is sufficient 1, 2
• Most "contraindications" to thrombolysis should be ignored in truly massive PE given the 52-65% mortality without treatment 1