Relationship between patent foramen ovale anatomical features and residual shunt after patent foramen ovale closure.

Transcatheter closure of patent foramen ovale (PFO) is an effective strategy for preventing recurrence of paradoxical embolism. However, PFO closure is often associated with residual shunt, which is a risk of recurrent stroke. This study aimed to evaluate the relationship between the anatomical features of PFO and residual shunt. The degree of residual shunt and its relationship with the anatomical features of PFO were evaluated in 106 patients who underwent PFO closure at our institution between March 2011 and January 2022 and in whom contrast transthoracic echocardiography was performed 1 year later. The mean PFO tunnel length was 9.3 ± 3.6 mm and the mean PFO height was 3.2 ± 2.2 mm. Atrial septal aneurysm (ASA) was found in 37 patients. After PFO closure, residual shunt was observed in 28 patients (grade 1, n = 8; grade 2, n = 16; grade 3, n = 3; grade 4, n = 1). Univariate logistic analysis identified ASA to be associated with residual shunt (odds ratio 2.78, 95% confidence interval 1.14 to 6.79; p = 0.024). There was no association of residual shunt with the size of the PFO, the length of PFO tunnel, or the size of the device used for closure. Two of four patients with a large residual shunt of grade 3 or grade 4 were found to have device size mismatch. Residual shunt after PFO closure was observed in a quarter of patients and was related to the presence of ASA. A few patients had a large residual shunt due to the device size mismatch.