metopolol

my husband and his mother are on this for high blood pressure and they take 50 mg a day and they get no side effects other than memory, forgetfullness sometimes. I was told i might have to take this medicine for my mitrovalve leak and arrythmias but only 25 mg a day instead. my question is..I always had low pressure not high and its around 100 over 60 sometimes 90/50 or 120/70. its never the same. Could this be a problem? I will give it a try but if I feel faint of slow heart beat I guess I will let my doctor know? I wonder why we cant get this in less of a dose instead of 25mg like 15mg in case people have problems like this? does anyone have a answer for this? and does this really help people with skip beats or pvcs or pacs or arrythmias? has anyone have success stories? from this medicine?