Does Syncope Raise Heart Rate And Cholesterol Levels?

Hi Doctor, I am suffering from syncope (Type not known) for the past 5 years. Suddenly I feel like dark and loss of consciousness for a while an back to normalcy. It may last only for a few seconds. First I consulted Neurologist. They dis a lot of tests including HUT , CT of brain, Doppler . And they ruled out any Neuro problem. They referred me to Cardiologists. They did many tests including Extended Holter for 72 Hrs. Till today nothing is found. But I am suffering from this problem periodically. Sometimes I fall on ground also. After the episode I feel my heart beat increases for a while. Now I am 60, My Sugar is normal. BP is 90-130. My Cholesterol level is slightly high. Total is 220 and LDL 153. Other normal. Can you please suggest something?