Orthostatic Hypertension

Recently I had an MI.  A stint and clot removal was the fix.  I am 45 with a cholestrol of 164. I don't smoke nor do I drink.  I used Meth for about 6 years prior to the MI.  I was off the drug for about a year when it (MI) happened. I was told that I have an enlarged aorta because of the MI.  My BP runs in the 125/80 range in a supine position and raises on average 20mm Hg on both the diastolic and systolic when I sit up.    How bad is this condition, and what is the long term prognosis.