I had my ASD repaired at age 32 as well. I was diagnosed after experiencing new onset PVCs, pre-syncope, and fatigue. There is a post-closure syndrome with he Amplatzer device - higher among people with Nickel allergy - that can cause shortness of breath, chest pain, etc. I experienced this syndrome and found I was highly allergic to nickel. Unfortunately, I did not find out about this adverse effect until after the surgery. There is growing evidence in the medical literature about this syndrome and risk with Amplatzer device and nickel allergy. The syndrome plagued me for about 9 months, prior to disappearing. For me, it improved slowly over the first 6 months. Once you start to grow cells (epithelialize) over the device, the nickel levels decrease in the blood stream and symptoms usually disappear for most people, although this varies. Some people respond to steroids, like prednisone, although the dose and duration are not consistent and results vary. I tried steroids, and preferred to have the shortness of breath and fatigue rather than the side effects of the steroids. Removal of the device is the other option - which includes open heart surgery. My cardiologist and I decided to give it 12-18 months to monitor my symptoms and then decide what to do next. I did not really want to have open-heart surgery so soon after the procedure (it has it's own risks), so I decided to wait it out and give it at least a year. I am glad I waited and coped with the symptoms. The symptoms were not fun, but for me, the symptoms did improve over time. The shortness of breath was easiest to get used to, but the fatigue was difficult, especially with two small kids and a full-time job. Good news - I am back to normal, full activity (running half-marathons, strength-training, etc) and no longer have any symptoms. It seems that there is growing information on this, but no good plan of attack or guidelines on how to deal with it. Each patient has varying experiences, so you will need to find out what works best for your situation. Good luck!!
Overall, I was lucky to have a cardiologist that did not think I was crazy when I presented the idea of nickel allergy and my symptoms. I know many patients from the forum have had a multitude of issues after ASD closure have had to try to convince cardiolgists, etc. of symptoms, issues. My cardiologist and I worked together on the issue, and he now thinks he has another patient with the syndrome as well. I am glad that at least something positive has come out of my experience. Again, good luck!