The aneurysm of the aorta requires surgical correction. Surgery is indicated when the aneurysm becomes symptomatic (back pain etc.) or when the aneurysm is expanding or has achieved a size of >5.5cms. In your fathers case, the size is 5.6 cm. I would suggest that if he has pain or any other symptoms referable to the aneurysm, he requires early surgery. If he does not have any symptoms then he may be kept under close follow up of cardiologist with review echocardiography every 3-6 months for monitoring any increase in the size of aneurysm. Besides his blood pressure needs to be kept strictly under control. It is recommended that you see a cardiothoracic surgeon with all reports for a final opinion.