Heart probs. can lead to dizziness - in some people. So, too, can too little hydration. I found out about it from my cardiologist following a vacation. I was on a pier and thought there was an earthquake, but... nope. Because I've nearly become impaled (by a picket), the advice my doc gave me was make sure that I am always well-hydrated and to immediately rest when I start feeling dizzy and to move slowly when changing positions. I'm also on heart med.

I am most interested to know what your testing may help your doctors determine. Please do let us know.