Predictors of Residual Right to Left Shunt in Patients Undergoing Percutaneous Transcatheter Patent Foramen Ovale Closure: A New Clue “Inferior Vena Cava-Patent Foramen Ovale Angle”

<b>Background:</b> Many different devices are currently used for percutaneous patent foramen ovale (PFO) closure (pPFOc), aiming to achieve complete occlusion to prevent recurrent embolism. We aimed to reveal the association between residual right-to-left shunt (RLS) after pPFOc and baseline structural features of the PFO determined using transoesophageal echocardiography (TEE) before the procedure. <b>Methods:</b> This is a single-center cross-sectional study. A total of 123 patients who underwent pPFOc for cryptogenic stroke (CS) were screened, consecutively. Patients were compared based on the presence of residual RLS. The association of structural features of the PFO with residual RLS was evaluated using logistic regression analysis. <b>Results:</b> The procedure was successfully completed in a total of 103 patients included in the study after exclusion and 21% had significant residual RLS. During a median follow-up of 18 months, one patient died at 25 months due to malignancy, recurrent CS were observed in 5 (5%) patients, and atrial fibrillation was detected in 3 (3%) patients. No significant difference was observed in the baseline clinical characteristics and laboratory parameters among the patients. In addition to atrial septal aneurysm (ASA), aortic rim, tunnel width and length; inferior vena cava (IVC)-PFO tunnel angle was associated with residual RLS with a cut-off 11.3 (AUC: 0.786, 64% sensitivity, 87% specificity, <i>p</i> < 0.001). In individuals with residual RLS, longer and wider tunnel size, rudimentary aortic rim, acute IVC-PFO tunnel angle, and decreased tunnel length-left disc ratio were observed. <b>Conclusions:</b> IVC-PFO tunnel angle is a novel parameter and provides benefit to detect significant RLS in pPFOc patients.