possible tachycardia or other

Last November I awoke in the early  hours  of the morning, heart racing incredibly fast,  it went on a few minutes and I called  an ambulance.   By the time I'd  been taken to the hospital the  crew  told me  it had diminished  from 130  something to 87, my   ambulance  ECG  was  'textbook'  normal.  The hospital ECG  too was  normal and they let  me go  home  after 2  hours.   I had in February and March a few  episodes,  some  when sat/on the phone  and when exercising.   I became  weak  and staggery  with one but managed to get home the two miles remaining with  a  struggle,  oddly  though  I began to feel 'normal'  once within sight of  home.  Another episode I'd been walking 2 minutes and my pulse  started to rise, and I got light headed  again,  ity  went to 160 beats and after  sitting down in a  nearby  shop it  was  still 140  after 15 mins and so I called  an ambulance  (again !)      ambulance crew  arrived, my pulse still 130  but ECG  'normal'  as  has  the primary care   doctors  subsequent ECG  proved.   After  20 mins  they let  me  walk home .    I  don't seem to have had  any since/   my SP02  has been  100 per cent when assessed  by ambulance crews.   I'm beginning to wonder could  thesde have been extended  and severe  anxiety  reactions.
I do have borderline hypertension, and apparenly  13mm   LVH  according to  echo.  My  resting pulse is  between  50  and  55 and for many years I have exercised between  4  and  6  times a week for up to an hour,
The ambulance crew  thought I looked  'fit'   Should I have a holter or  exercise testing

[CCF HeartMD5]

With your symptoms of palpitations, It may be reasonable to consider holter monitoring rather than exercise testing in your situation in order to rule out brief episodes of a very rapid heart rate that have not been detected by any other method thus far. You should discuss the pro's and con's of exercise testing with your physician.

[XFACTOR2009]

Thank you,  I will ask if my primary care  doctor can arrange it.  In the meantime I have purchased my own  ECG handheld event monitor and should my  heart start to race again I will attempt to record  it.