Matt Whiting writes:

I'm guessing that is the BP the doc is looking for while taking the
meds. It needs to be unusually low with the meds if it is to stay low
enough without the meds.

Maybe. But if the meds counteract the body's own attempts to raise BP it may
never drop that low, simply because the body keeps raising it to more normal
levels. Thus, you never get off the meds. The only way to see if it's normal
without medication is to stop the medication, but most doctors won't risk
that. The bad effects of hypertension are well documented, and doctors don't
want to run the risk that the BP would run away if the meds were stopped.