vaso vagal syncopy

Two cardiologists have suggested that my periodic fainting spells could be vaso vagal syncopy (VVS).  I've experienced 4 or 5 episodes over +/- 8 years.  Each one began with an incredible pain toward the center of my chest.  Thinking that the pain was heart burn (I do have frequent intense heart burn), I arose to take an antacid tablet.  On rising the pain continued with a feeling of lightheadedness/dizziness, feeling extremely hot, sweating, clammy and somewhat disorented.  Then I apparently pass out because I find myself on the floor.  After awakening, I experience extreme cold and some weakness, but otherwise refreshed and without the elephant on my chest.

I've had nuclear stress test, ultrasound, event monitor, and tilt-table test.  All the tests proved negative.  Is it possible that my symptoms are indeed caused by vaso vagal syncopy of could they be from something else?  If the latter, what other conditions could cause the symptoms?  Or, if you also suspect VVS, what is the treatment?