Glad to hear your brother didn't have a stroke. Years ago I worked with a gal who's blood pressure was always a little low, and I remember going shopping with her during lunch one day, and we were standing at the checkout line when she grabbed my arm and said she was about to faint.
Every one who worked there got nervous when she nearly collapsed (the manager got her a chair real quick), but I told them her BP is usually a bit low. The manager got her a small glass of sherry, and she perked right up. Needless to say, her condition wasn't as bad as your brother's seems to be, but checking the meds to see what he can take, perhaps a lower dosage might just do the trick.
As for stress tests and such, I take a full set of them once a year, and so far (knocks wood), I pass with flying colors every year, but at our age, you never know when that'll change, so even though It's a 4-5 hour stint at the Cardiologist's office, I'd rather that than having to wonder how I'm doing.
BTW, don't you take some kind of cholesterol medication? Mine's usually less than half what yours is, but I take a low dose cholesterol medication to keep it in check.