What is the likelihood that Pulmonary Embolism (PE) causes Ischemic Stroke?

From the Guidelines

Pulmonary embolism (PE) is unlikely to directly cause ischemic stroke in most cases, but the connection between PE and ischemic stroke exists in specific circumstances, such as when a patient has a patent foramen ovale (PFO). The presence of a PFO in patients with PE increases the risk of ischemic stroke, with a relative risk of 5.9, as reported in a study published in Circulation 1. This study highlights the importance of considering PFO in patients with PE, as it can lead to paradoxical embolism, where a blood clot bypasses the lungs and reaches the brain's arteries, causing an ischemic stroke.

Key Points to Consider

• The connection between PE and ischemic stroke is primarily related to the presence of a PFO, which occurs in approximately 25% of the general population.
• Patients with both PE and PFO are at a higher risk of ischemic stroke due to paradoxical embolism.
• Severe right heart strain from a massive PE can also lead to right-to-left shunting through a PFO, increasing the risk of ischemic stroke.
• Patients with hypercoagulable states who develop PE may be at higher risk for concurrent stroke due to their underlying tendency to form clots throughout the body.

Treatment and Prevention

• Standard anticoagulation therapy, such as heparin followed by warfarin, or direct oral anticoagulants like apixaban or rivaroxaban, can treat PE and reduce stroke risk by preventing new clot formation.
• Screening PE patients for PFO by adding a bubble study to routine transthoracic echocardiography can increase the detection of impending paradoxical embolism, as reported in the study published in Circulation 1.
• Aggressive therapeutic options, including catheter-based techniques, surgical embolectomy, and appropriate antithrombotic therapy, may be considered for patients with an intracardiac shunt and PE.

From the Research

Likelihood of Pulmonary Embolism (PE) Causing Ischemic Stroke

The likelihood of Pulmonary Embolism (PE) causing Ischemic Stroke is a complex topic that has been studied in various research papers.

• The studies suggest that PE can increase the risk of ischemic stroke, particularly in patients with a patent foramen ovale (PFO) 2, 3, 4.
• A systematic review and meta-analysis found that PFO was significantly associated with ischemic stroke in patients with PE, with an odds ratio of 5.36 (95% CI 3.20-8.99, p < 0.00001) 3.
• Another study found that ischemic stroke occurred in 17.1% of patients with intermediate-risk PE, and was always associated with PFO and large shunt 2.
• A case series and literature review found that the clinical outcomes were favorable in 47.05% of patients with concomitant AIS and PE, while 41.17% had poor outcomes (severe disable symptoms or death) 5.

Patent Foramen Ovale (PFO) and Ischemic Stroke

• PFO is a common condition in patients with acute PE, and is associated with a higher incidence of ischemic stroke and increased mortality 3, 4.
• Transesophageal echocardiography (TEE) is a more efficient method for diagnosing PFO than transthoracic echocardiography (TTE) 2.
• The presence of PFO can lead to paradoxical systemic embolization, including cerebral embolism, ultimately leading to acute ischemic stroke (AIS) 4.

Treatment and Management

• The treatment of concomitant PE and AIS is complex, and requires careful evaluation of the risks and benefits of therapies such as intravenous thrombolysis, mechanical thrombectomy, and catheter-directed thrombolysis 5, 4.
• Systemic thrombolysis and surgical thrombectomy seem to be effective management options, but further studies are needed for validation 4.
• Anticoagulation alone is also a common treatment modality, but has a lower survival rate compared to thrombolysis and surgical thrombectomy 4.