It's absolutely normal to have an angiography. Angiography is just a test just like x ray or CT scan. It changes nothing and does not cause any major problems to the body. In angiography we insert a contrast dye inside the body by IV injection and then check the blood flow under an x-ray fluoroscopy just like CT scan. This procedure does have small risk of complications because it's invasive a needle is involved and the dye used can can rarely have some allergic reaction or renal dysfunction... But the incidence is very rare. You can safely let your fiance go through this procedure and marry him afterwards without worrying about anything