Given your atrial fibrillation and atrial septal aneurysm, you should seek consultation with a cardiologist
specializing in these disorders. I strongly encourage you to see a specialist at an academic medical center (usually affiliated with a medical school), and someone who specializes in adult-congenital heart disease may have the most experience with this.
An atrial septal aneurysm is an extremely rare finding. During embryologic development, there is a hole between our two atria (chambers at the top of the heart) that allows blood to bypass the lungs. After we are born, blood then needs to flow to the lungs, as this hole closes. An atrial septal aneurysm is an abnormal out-pouching of tissue in the area where this hole usually closes. A patent foramen ovale is extremely common. It occurs when this hole does not completely close.
There is concern in the academic literature that patients with an atrial septal aneurysm are at increased risk for stroke. It is possible that the aneurysm, depending on its location, has caused enlargement of your left atrium, which increased your risk for developing atrial fibrillation. Because the combination of issues you are having is extremely rare, you will need a cardiologist to help determine if you require surgery
, catheter-based intervention, blood thinners, or close monitoring. You may required additional ultrasounds or even a cardiac MRI