Introduction: Proper defect sizing and device size selection are imperative for ensuring successful clinical outcomes after transcatheter patent foramen ovale (PFO) closure. However, with current sizing techniques, residual shunting remains as high as 25% and is associated with an increased risk of recurrent neurologic events. Since 2017, we adopted a PFO sizing strategy based on right atrial (RA) tunnel “width” oversizing utilizing three-dimensional transesophageal echocardiography (3D-TEE). Hypothesis: We hypothesized that the PFO tunnel width at the RA opening and a cover index based on this dimension would predict residual shunting at long term follow-up. Methods: Sixty-four patients underwent transcatheter PFO closure (60 patients utilizing a 3D-TEE based oversizing strategy) at our institution between 2015 and 2022. PFO tunnel length, tunnel width at RA opening, and tunnel width at left atrial opening were determined by 3D-TEE either before or at the time of closure. We determined an absolute PFO “cover index” for each patient as follows: RA disc diameter - RA tunnel width. Receiver operating characteristic (ROC) curve analysis was used to determine the predictive ability of 3D-TEE derived PFO dimensions and the PFO cover index to predict residual shunting at follow-up. Results: Fifty-one of sixty-four patients had a long-term follow-up bubble study (mean follow-up time 8.0±3.7 months). Of the 47 patients closed utilizing a 3D-TEE based sizing strategy and with a follow-up bubble study, only 5 patients (10.6%) had residual shunting at follow-up. Of the three 3D-TEE based PFO dimensions, only the RA tunnel width was predictive of residual shunting at follow-up (AUC 0.84, p=0.004). A cutoff of 15.5 mm or greater for RA tunnel width had the best combination of sensitivity (86%) and specificity (73%). The PFO cover index was also strongly predictive of residual shunting at follow-up (AUC 0.87, p=0.002). A cutoff of 9.5 mm or less had the best combination of sensitivity (86%) and specificity (82%). Conclusions: A larger PFO tunnel width at the right atrial opening and a lower cover index based on this dimension predict residual shunting at follow-up. Our findings have important implications for improving sizing strategies for transcatheter PFO closure.
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