Objective:

To describe the incidences of intrapulmonary shunt (IPS) and patent foramen ovale (PFO) in a population of adults with embolic stroke of undetermined source (ESUS). 

Background:

ESUS is defined as ischemic stroke of undetermined etiology but whose underlying mechanism is likely embolic. There is a growing body of evidence which implicates IPS as a rare cause of ESUS. We conducted a descriptive analysis to describe the rates and characteristics of IPS and PFO in a population of adults with ESUS. 

Design/Methods:

This was a retrospective chart review of 725 patients presenting to a single comprehensive stroke center with ESUS between April 2017 and April 2022. Clinical and demographic information was collected, including age, sex, prolonged cardiac monitoring, transesophageal echocardiography (TEE) findings, and incidence of stroke recurrence within three years of initial admission. Differences in age and stroke recurrence between patients with IPS, PFO, or neither were evaluated using univariable linear regressions at α<0.05. 

Results:

Patients who had evidence of atrial fibrillation on prolonged cardiac monitoring were excluded (n=112; 15.4%). Of the remaining 613 patients who received a diagnosis of ESUS, 102 (16.6%) were found to have a PFO and 30 (5%) were found to have an IPS on TEE. Patients with an IPS were younger than those without TEE abnormalities (57 years vs. 62 years; p<0.05), and were more likely to have a recurrent stroke within three years of their initial hospital admission (23.7% vs. 10.1%; p=0.03). IPS patients were similarly more likely to have a recurrent stroke than PFO patients (26.7% vs. 8.82%; p=0.02), but did not show a significant difference in age (p=0.94). 

Conclusions:

IPS is an uncommon but potentially important TEE finding that may contribute to the pathogenesis of ESUS. Further investigation is needed to determine IPS as an independent risk factor for ESUS.