Hi Jenny, I said I'd ask my Sis what her dh's problem was with the dizziness and blackouts so here is her response. (Something you could ask the doc to check anyway.)
He has what is called "hypertrophic cardiomyopathy". It is a condition that is familial, or passed on down the line in his family, and it is a ballooning of the verntrical into the heart wall, which doesn't allow a proper flow of blood. This is what causes his dizziness and caused his many falls over the years. We always thought it was his ears, since his doctor always sent him to have his ears checked. He's been fine since he's been on his pills. Although today, he could feel something whenever he walked or climbed the stairs.
HTH