An atrial septal aneurysm will be diagnosed when the atrial septum extended (bulged) at least 1.1 cm of the left or the right atrium, or both. The size of the aneurysm can be classified as either 1.1cm to 1.4 cm (moderate) or 1.5 cm or more (severe).
Hope this give you a perspective, and it appears your aneurysm size is below the threshhold metric. Thanks for sharing, take care
Ken