Can Pulmonary Embolism Cause Stroke?
Yes, pulmonary embolism can cause stroke through paradoxical embolism when a patent foramen ovale (PFO) is present, creating a right-to-left shunt that allows venous thrombi to bypass the lungs and enter the systemic arterial circulation.
Mechanism of PE-Related Stroke
The pathway for PE to cause stroke requires specific anatomical and hemodynamic conditions:
Patent foramen ovale is the critical anatomical link that allows paradoxical embolism to occur, with right-to-left shunting caused by inverted pressure gradients between the right and left atrium during acute PE 1
Increased right atrial pressure from PE creates the hemodynamic conditions necessary for right-to-left shunting through a PFO, allowing venous thrombi to bypass pulmonary filtration and enter systemic circulation 1
Thrombus can become trapped within the PFO itself (impending paradoxical embolism), representing an extremely high-risk situation for stroke 1
Clinical Impact and Risk Magnitude
The presence of PFO dramatically increases stroke risk in PE patients:
Patients with PE and PFO have a 5.9-fold increased risk of ischemic stroke compared to PE patients without PFO (relative risk 5.9) 1
Silent brain infarcts occur in 33% of PE patients with PFO versus only 2% in those without PFO 1
PFO presence also increases mortality risk 2.4-fold and peripheral arterial embolism risk 15-fold in PE patients 1
PFO is an independent predictor of adverse events in acute PE, warranting more aggressive management 1
Screening and Detection
Current guideline recommendations for PFO screening in PE:
Screening for PFO may be considered in massive or submassive PE using echocardiography with agitated saline bubble study or transcranial Doppler for risk stratification (Class IIb recommendation) 1
Adding bubble study to routine transthoracic echocardiography increases detection of impending paradoxical embolism in PE patients 1
Echocardiography can identify right-to-left shunt through PFO and presence of right heart thrombi, both associated with increased stroke risk 1
Management Implications
When PE and PFO coexist, treatment strategy should be escalated:
Surgical embolectomy may be considered for impending paradoxical embolism (thrombus trapped within PFO), as it may result in the lowest stroke rate (Class IIb recommendation) 1
Aggressive therapeutic options should be considered including catheter-based techniques, surgical embolectomy (particularly if intracardiac thrombus identified), and appropriate antithrombotic therapy 1
Thrombolysis may be associated with highest mortality compared to surgery or medical treatment with heparin in impending paradoxical embolism 1
Additional Stroke Risk Context
Beyond paradoxical embolism, the relationship between PE and stroke includes:
Patients with VTE have increased risk of subsequent stroke even without documented PFO, suggesting shared vascular risk factors 1
PE is the third most frequent cardiovascular cause of death after stroke and myocardial infarction, highlighting the severity of both conditions 2
Simultaneous presentation of PE and acute ischemic stroke is rare but creates complex management dilemmas regarding thrombolysis and anticoagulation 3
Critical Pitfalls to Avoid
Do not assume all PE-related strokes are embolic—the mechanism requires PFO presence and right-to-left shunting 1
Do not overlook screening for PFO in high-risk PE patients (massive or submassive), as this finding fundamentally changes management 1
Do not routinely use thrombolysis for impending paradoxical embolism—surgical approaches may offer better stroke prevention 1
Recognize that PFO closure timing in the setting of acute PE and paradoxical embolism remains an unanswered clinical question requiring individualized assessment 1