This study aims to investigate (1) the de novo cerebral microembolization in patients who undergo transcatheter closure of PFO or ASD, and (2) evaluate the relationship between de novo cerebral microembolization and in situ thrombus within PFO.

Patent foramen ovale (PFO) is prevalent in the general population and it is commonly accepted that PFO is associated with various pathological conditions, including ischemic stroke, transient ischemic attack, migraines, and systemic or coronary embolization. In situ thrombus formation may play a role in patients with PFO-associated stroke or migraines. After transcatheter closure of PFO, peri-interventional cerebral embolic lesions have been detected. This study aims to investigate (1) the de novo cerebral microembolization in patients who undergo transcatheter closure of PFO or ASD, and (2) evaluate the relationship between de novo cerebral microembolization and in situ thrombus within PFO.

PFO group

Inclusion Criteria:

1) age 18 to 65 years; 2) documented PFO with medium-to-large shunts (≥ 20 microbubbles by c-TCD at rest or during the Valsalva maneuver); 3) history of embolic stroke (based on brain magnetic resonance imaging within 24 hours after symptom onset) or TIA within 6 months without other identifiable causes; 4) history of migraine for more than one year without other identifiable causes; 5) asymptomatic group: incidental finding of PFO in asymptomatic individuals, and presence of high-risk activities and/or anatomical features related to PFO (high-risk activities were defined as those in which the Valsalva maneuver was performed frequently or those that increased the risk of venous gas formation; and high-risk anatomical features included atrial septal aneurysm and/or curtain pattern on c-TCD).

Exclusion Criteria:

1) presence of any known vascular risk factor, including hypertension, hypercholesterolemia, diabetes mellitus, atrial fibrillation, smoking and obesity; 2) history of embolic stroke or TIA within the past one month; 3) history of deep vein thrombosis or pulmonary embolism; 4) presence of coronary artery disease and carotid artery lesions; 5) presence of coexistent cardiovascular structural malformations or diseases; 6) allergy to contrast medium; 7) refusal to participate.

ASD group

Inclusion Criteria:

1) age 18 to 65 years; 2) secundum ASD size 10 to 20 mm, with sufficient surrounding rims, except the aortic rim; 3) right heart catheterization: resting SPAP < 50 mm Hg, Qp/Qs ≥ 1.5 and PVR < 5 WU.

Exclusion Criteria:

1) presence of any known vascular risk factor, including hypertension, hypercholesterolemia, diabetes mellitus, atrial fibrillation, smoking and obesity; 2) associated with other cardiac abnormalities or diseases; 3) resting SPAP ≥50 mm Hg and resting PVR ≥5 Wood units;4) primum or sinus venosus type ASD; 5) presence of intracardiac thrombi, permanent contraindications to platelet therapy, and allergic reaction to nickel.

In this study, there are two groups of the patients who will undergo transcatheter closure. (1) PFO patients (n=600); (2) ASD patients (n=200). Before transcatheter closure, all patients will undergo brain DW-MRI. After the transcatheter closure, DW-MRI will be performed 24 hours and 4 weeks postoperatively. In addition, the presence or absence of in situ thrombus within the PFO will be determined in patients with PFO.

he data that support the findings of this study are available from the corresponding author upon reasonable request.