High-Risk Pulmonary Embolism with Haemodynamic Instability After Systemic Thrombolysis Failure

This protocol applies to acute pulmonary embolism presenting with haemodynamic instability — including cardiac arrest requiring CPR, obstructive shock, or persistent hypotension — when initial systemic thrombolytic therapy has failed to achieve stabilisation or is contraindicated.

Clinical Scenario

High-risk PE is defined by haemodynamic instability, which encompasses any of the following:

• Cardiac arrest requiring cardiopulmonary resuscitation
• Obstructive shock: systolic blood pressure <90 mmHg, or vasopressors required to achieve blood pressure ≥90 mmHg despite adequate filling, with end-organ hypoperfusion
• Persistent hypotension: systolic blood pressure <90 mmHg or drop ≥40 mmHg lasting >15 minutes, not caused by new-onset arrhythmia, hypovolaemia, or sepsis

When First-Line Treatment Has Not Worked

First-line management of high-risk PE combines systemic thrombolytic therapy with intravenous unfractionated heparin anticoagulation, plus haemodynamic and respiratory support. This protocol is indicated when that approach has failed to achieve:

• Correction of hypoxaemia (arterial oxygen saturation ≥90%)
• Haemodynamic stabilisation (systolic blood pressure ≥90 mmHg)
• Resolution of clinical instability and improvement of right ventricular dysfunction on echocardiography by 36 hours

Next-Step Approach

When systemic thrombolysis fails or is contraindicated, alternative reperfusion strategies — either surgical or catheter-based — become the focus. In cases of refractory circulatory collapse or cardiac arrest, mechanical circulatory support may be added alongside reperfusion. The specific indications, sequencing, and decision criteria are detailed in the full structured protocol.