Many causes of atrial fibrillation (heart beating irregularly)but reading your post, then your AF is due to aortic valve disease, seemingly not too bad.
40 years ago, the commonest cause would have either have been syphilis or the results of rheumatic fever, but today, the commonest cause by far, is old age, ageing arteries.
From what you have typed, that is not too bad for an ECG report....;-)
There is no mention of ischaemia (damaged heart muscle ) or enlargement, of any of the chambers of the heart, so.......well done.......it could have been worse, much worse.
Tablets will sort you out.