The sponsor's study closure justification addressed the 522 Order's questions.

Prospective, multicenter, case-cohort study.To identify potential risk factors associated with the occurrence of erosion due to implantation of the AMPLATZER™ Septal Occluder (ASO.)

This study will enroll 8000 subjects. The sub-cohort will consist of 160 (2%) subjects, randomly selected from the full cohort. The analysis population will consist of all subjects in the sub-cohort, combined with all subjects with erosion events who are not in the sub-cohort. A detailed assessment of risk factors will be conducted on the subjects in this analysis population.

Inclusion Criteria:

To participate in this clinical investigation, the patient must meet all of the following inclusion criteria:

1. Patient indicated for ASD closure who has echocardiographic evidence of ostium secundum atrial septal defect and clinical evidence of right ventricular volume overload (such as, 1.5:1 degree of left-to-right shunt or RV enlargement) and is implanted with the ASO device Note: This does not include the indication for closure of a fenestration following a fenestrated Fontan procedure
2. Patient is willing and able to complete the follow-up requirements of this study
3. Patient signs the informed consent (or a legal representative signs the informed consent.)

Exclusion Criteria:

Patient is not eligible for clinical investigation participation if he/she meets any of the following exclusion criteria:

1. Patient is known to have extensive congenital cardiac anomaly which can only be adequately repaired by way of cardiac surgery
2. Patient is known to have sepsis within 1 month prior to implantation, or any systemic infection that cannot be successfully treated prior to device placement
3. Patient is known to have a bleeding disorder, untreated ulcer, or any other contraindications to aspirin therapy (unless another anti-platelet agent can be administered for 6 months)
4. Patient is known to have a demonstrated intracardiac thrombus on echocardiography
5. Patient whose size (such as, too small for transesophageal echocardiography probe, catheter size) or condition (active infection, etc.) would cause the patient to be a poor candidate for cardiac catheterization
6. Patient has margins of defect that are less than 5 mm to the coronary sinus, AV valves or right upper lobe pulmonary vein

Patients indicated for ASD closure have echocardiographic evidence of ostium secundum atrial septal defect and clinical evidence of right ventricular volume overload (such as, 1.5:1 degree of left-to-right shunt or RV enlargement).

The subject population includes vulnerable patients.