Iatrogenic atrial septal defects after transseptal puncture are not related to measures of atrial cardiomyopathy

Introduction: Transseptal puncture (TSP) is a standard procedure in various cardiac interventions, including atrial fibrillation ablation. A number of patients develop an iatrogenic atrial septal defect (iASD) post-procedure. This study aims to investigate whether atrial cardiomyopathy (incl. left atrial pressure) is a relevant risk factor for the occurrence of iASD upon TSP.

Methods: This retrospective analysis included patients who underwent radiofrequency ablation for atrial fibrillation at our clinic from August 2013 to September 2023. Patients received preprocedural transesophageal echocardiography (TOE) to evaluate the intraatrial septum and exclude left atrial appendix thrombosis as part of the standard care. Left atrial pressure and 3D electroanatomical voltage maps were obtained during the procedure. The cohort was divided into three groups based on TOE findings: patients without ASD, patients with iASD after a previous transseptal puncture, and patients with patent foramen ovale (PFO). Primary demographic data, left atrial volume index, and left atrial pressures were assessed for each group, along with the total left atrial wall area and the extent of the low-voltage regions using 3D electroanatomical mapping.

Results: 200 patients presenting for redo ablation (all cases underwent a primary TSP with a 15 Fr deflectable sheath 21.8 ± 27.1 months before the second ablation) were included. Of these, 178 individuals presented with a competent atrial septum, 13 with a PFO, and nine with an iASD. The mean iASD diameter was 3.6 ± 1.0 mm. Visual left-to-right shunting was documented in 46.2% of the PFO and 55.6% of the iASD cases. Statistical analysis showed no significant differences in age (p=0.819), BMI (p=0.371), and BSA (p=0.373). The left atrial volume index showed borderline significance (p=0.046). Pairwise comparisons revealed notably lower volumes in patients with PFO (33 ml/m² ± 7.4) compared to those with iASD (47 ml/m² ± 15.5, p=0.054) and without ASD (44 ml/m² ± 17.6, p=0.137). No significant difference was found between patients with iASD and those without ASD (p=1). Additionally, no relevant differences were found in mean left atrial pressure (p=0.620), left ventricular ejection fraction (p=0.122), NT-proBNP levels (p=0.560), or the CHA2DS2-VASc-Score (p=0.365). The total area assessed during 3D electroanatomical mapping showed no significant divergence across all groups (p=0.988). To evaluate the degree of atrial cardiomyopathy, we quantified the total left atrial wall area and the global low-voltage area and analyzed their relationship. A chi-square test with Monte Carlo simulation (10,000 samples) was used to compare the proportion of the low-voltage regions among the three groups, revealing no significant variation (p=0.098).

Conclusion: The findings suggest that there is no significant association between measures of atrial cardiomyopathy, including left atrial pressure or the degree of left atrial low voltage, and the occurrence of iatrogenic septal defects.