Bubble-test for detection of a patent foramen ovale in young to middle-aged ischemic stroke patients

Background: Current stroke guidelines do not recommend routine screening for a patent foramen ovale (PFO) in patients with acute ischemic stroke (AIS) of undetermined cause. This study evaluated the diagnostic accuracy of the transcranial Doppler bubble test (TCD-bubble) for PFO detection in younger AIS patients. Patients and methods: Data from a prospective institutional stroke registry were retrospectively analyzed, including AIS patients aged ≤65 years treated with intravenous thrombolysis (IVT) and/or endovascular therapy (EVT) over 5 years. Right-to-left shunt (RLS) was assessed using the TCD-bubble test. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for PFO detection were calculated using transesophageal echocardiography (TEE) as the reference. Furthermore, we included a ROC-analysis to provide a bubble-threshold and calculated a new sensitivity, specificity, PPV and NPV. Results: Of 383 patients, 120 (31%) underwent TCD-bubble testing: 61 (50.8%) had no RLS, 20 (16.7%) had RLS only during the Valsalva maneuver, and 39 (32.5%) had RLS at rest. Cardiovascular risk profiles and functional outcomes did not differ between RLS-positive and -negative patients. Among 87 patients with TEE, PFO was confirmed in 69.4% of RLS-positive cases (PPV), while a negative TCD-bubble test excluded PFO in 97.4% (NPV). Sensitivity and specificity were 97.1 and 71.2%, respectively. A cut-off of ≥3 bubbles in TCD-bubble testing resulted in a sensitivity of 91.4% and specificity of 88.5% for PFO detection. Conclusion: The TCD-bubble test is a reliable, non-invasive screening tool for PFO in younger AIS patients with high sensitivity and NPV for PFO detection. A positive result warrants confirmatory TEE, while a negative test may preclude further invasive evaluation.