Multicenter study on transcatheter closure of large secundum atrial septal defects using 40–50 mm septal occluders

Objective: Transcatheter closure of secundum atrial septal defects is well-established, but data on very large defects requiring 40–50 mm occluders remain limited. This multicenter retrospective study evaluated the safety and efficacy of percutaneous closure using large atrial septal occluders. Methods: Patients undergoing atrial septal defect device closure with 40–50 mm occluders from June 2015 to May 2025 at two tertiary centres were analysed. Patients were grouped by device size: Group A (40–42 mm; n = 34) and Group B (44–50 mm; n = 28). Results: The cohort ( n = 62) had a mean age of 42.07 years with female predominance (70.96%). Mean atrial septal defect size was 33.03 mm (thick-to-thick: 38.71 mm), with mean pulmonary artery pressure of 22.33 mmHg and left ventricular end-diastolic pressure of 12.59 mmHg. Aneurysmal septum with thin or deficient posteroinferior rim was common (77.4% and 19.4%, respectively). Procedural success was 93.5%. Device instability or residual flow led to surgical closure in three cases; one had intraprocedural embolisation. Procedural assistance (balloon/device, etc.) was needed in 93.5%. Fenestrated devices were used in four (6.5%) patients—due to severe pulmonary stenosis, diastolic dysfunction, or pulmonary hypertension. “Cobra” configuration and device bulkiness were noted in 9.7% and 6.5%, respectively. Arrhythmias occurred in 25.8%, mostly transient. One patient developed device-related endocarditis, and one late, unrelated death occurred due to intracranial haemorrhage. At a mean follow-up of 29.29 months, outcomes were satisfactory. Conclusion: Transcatheter closure of large atrial septal defects with 40–50 mm devices is safe and effective with proper anatomical assessment, procedural planning, and vigilant follow-up in selected patients.