Hello there. I'm 33 and at the moment I'm waiting for blood results and to have an ecg on my heart. On getting a fitbit in July I discovered that my heart rate would fly up during normal excercise like walking (122 to 135 to even 170 once!!!). In 2010 I had episodes where I had lots of palpitations and had an mri, ecg, stress test and nothing found (all in Ireland), my British GP thinks we probably won't find anything over on this side of the Irish sea either. I have to agree with him to be honest as a lot of tests have already been done. I'm currently on 2.5 of beta blockers which don't seem to making a difference to the heart rate. I'll chat to my doctor next week about putting the beta blockers up to 5 but where will that leave me? I'm assuming once my heart is slower I can excercise more and thus try to lower the rate overall. Just wondering if this has happened to anyone else, where lots of tests have been done but no conclusion come to? I have General Anxiety Disorder which leaves me quite anxious all the time so I suspect that may be adding to it....thanks for any replies, Grace.