Pulmonary Embolism and Right-to-Left Shunts (PEaRLS)

April 2, 2026 updated by: Tufts Medical Center

Every fetus has a small hole in their heart, called a foramen ovale when they are developing in the womb. For most people this hole closes shortly after birth, but it doesn't close completely in 1 out of every 4 people. This is called a "patent" foramen ovale, or PFO. In people with a PFO it is possible for a blood clot in a vein to enter the heart, pass through the opening, and then go into an artery - this is referred to as a paradoxical embolism which passes through a "Right-to-Left Shunt," or RLS. If this occurs, the blood clot can cause a stroke. The most common RLS (more than 90%) is a PFO. Much rarer causes include other types of holes in the heart (like an atrial septal defect, or ASD), or a vascular communication in the lungs (like a pulmonary arteriovenous malformation, or AVM).

We are investigating whether people with a PE are at higher risk of stroke if they happen to have an RLS compared to PE patients who don't have an RLS. This study will simply observe and compare the differences in stroke-related outcomes between those 2 groups.

Participation in the study last roughly 90-days and includes the following activities:

  • The study team will review your medical records to collect general information such as your age, sex, race/ethnicity, height, weight, medications, medical history, and other medical information
  • Magnetic Resonance Imaging (MRI) of your brain will be done as soon as possible following your enrollment in the study. For more information on MRI scans, please see the "MRI scan" section below.
  • A Transcranial Doppler (TCD) with bubble study will be performed to determine if an opening is present in your heart or lungs. TCD is performed using ultrasound. A contrast called agitated saline will be injected into your vein for this test.

  • You will be asked to return for a follow-up visit 90 days after your pulmonary embolism. At this visit, the following will occur:

    1. A second MRI of your brain will be performed.
    2. You will complete a questionnaire to evaluate whether you may have had a stroke since being discharged from the hospital
    3. You will meet with a member of the study team who will collect information about your health status.

Study Overview

Status

Recruiting

Conditions

Study Type

Observational

Enrollment (Estimated)

256

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • Massachusetts
      • Boston, Massachusetts, United States, 02111
        • Recruiting
        • Tufts Medical Center
        • Contact:
        • Principal Investigator:
          • David E Thaler, MD, PhD

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

Study participants will be selected from the population of patients admitted to Tufts Medical Center

Description

Inclusion Criteria:

  1. Age ≥18
  2. Acute pulmonary embolism (any grade/size)
  3. Patient or legally authorized representative is able to provide consent to participate in the study

Exclusion Criteria:

  1. Patients who, in the opinion of the study investigators, are unable to participate in required study activities
  2. Patients unable to undergo MRI imaging

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Right-to-Left Shunt (RLS)
The RLS cohort includes: a) Subjects found to have a right-to-left shunt (RLS) using transcranial Doppler (TCD) with bubble study b) Subjects with a known RLS (i.e. previously investigated with TCD or TEE)
No Right-to-Left Shunt (No RLS)
The No RLS cohort includes: a) Subjects with no RLS identified via TCD with bubble study b) Subjects known to not have an RLS (i.e. previously investigated with TCD or TEE)

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Combined incidence of acute ischemic stroke and silent cerebral infarct
Time Frame: 90 Days
  1. Acute ischemic stroke incidence through 90 days defined as an acute focal neurological deficit presumed to be due to focal cerebral or retinal ischemia and either: a) Persisting >24 hours b) Persisting <24 hours but associated with a neuroanatomically relevant cerebral or retinal infarct documented with MRI or CT or direct retinal observation.
  2. Silent cerebral infarct through 90 days defined as the presence of at least one new hyperintense lesion of 3 mm or greater in diameter on T2-weighted MRI between the screening MRI and the 90-day MRI in the absence of a relevant clinical event.
90 Days

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Tufts Medical Center

Collaborators

Occlutech International AB

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

January 30, 2026

Primary Completion (Actual)

February 18, 2026

Study Completion (Estimated)

January 1, 2028

Study Registration Dates

First Submitted

April 2, 2026

First Submitted That Met QC Criteria

April 2, 2026

First Posted (Actual)

April 9, 2026

Study Record Updates

Last Update Posted (Actual)

April 9, 2026

Last Update Submitted That Met QC Criteria

April 2, 2026

Last Verified

April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • STUDY00006524

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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