Which are hidden heart diseases manifested with palpitations and dizzy spells that are not being diagnosed with echo and ekg & require further tests?

Atherosclerosis, : typically stating later childhood, is dominant issue underlying cardiovascular disease; does not show on echo/EKG (only ↓ function from death of millions cells does). Disease is in the wall of the arteries (not the openings) & invisible by most current technology. Intravascular ultrasound, where done, is best research technology. Hi-Quality US of carotid bifurcations/femoral artery walls may show.