Correlation Between Interatrial Septal In Situ Thrombus and Stroke Evaluated by Transesophageal Echocardiography

Patent foramen ovale (PFO) is a crucial etiology of cryptogenic stroke, with paradoxical embolism recognized as its classic pathogenic mechanism. However, the origin of most emboli remains unclear. This study aimed to detect the presence and location of in situ thrombus on the interatrial septum in patients with PFO using contrast-enhanced transesophageal echocardiography (c-TEE) and analyze its correlation with stroke and migraine, thereby providing novel insights into the pathogenesis of PFO-related diseases.

A retrospective analysis was performed on 3343 patients who underwent TEE examination between March 2021 and December 2024. Patients were divided into the in situ thrombus group (n = 62) and the non-in situ thrombus group (n = 1211) based on TEE findings. According to clinical symptoms, patients were categorized into the stroke group (n = 210), the migraine group (n = 633), and the asymptomatic group (n = 430). TEE was used to comprehensively assess the location, size, and quantity of the in situ thrombus. The anatomical parameters and hemodynamic parameters of PFO were compared among different groups.

Among 1273 PFO patients, the overall detection rate of in situ thrombus on the interatrial septum by TEE was 4.56% (62/1273). The detection rate of in situ thrombus in the stroke group (11.90%, 25/210) was significantly higher than that in the migraine group (2.53%, 16/633) and the asymptomatic group (3.95%, 17/430) (p < 0.001). In situ thrombus was most commonly located on the right atrial surface of the interatrial septum (69.0%, 40/62). The PFO diameter in the thrombus group was significantly larger than that in the non-thrombus group (p = 0.0033), and the shunt velocity was also significantly higher (p < 0.001). At the same time, no significant difference in PFO length was observed between the two groups. All patients with a detected in situ thrombus had negative findings on lower-extremity venous ultrasonography. After PFO closure, the rate of symptom improvement in the stroke group was significantly higher than in the migraine group (95.68% vs 52.80%, p < 0.005).

c-TEE is an effective method for detecting in-situ thrombus in the atrial septum in patients with PFO, and such thrombus may play an important role in PFO-related stroke. PFO closure may be effective in stroke patients with concomitant in-situ thrombus. In clinical practice, routine risk stratification should be performed in patients with PFO, with an emphasis on identifying high-risk features and in situ thrombus lesions, to provide a basis for individualized treatment decisions.