Hi Smurph - Sounds like you are having the exact same estrogen-sensitivity issues I had. If you scroll down and look at other recent posts (or use the search box for 'palpitations'), you'll find my posts about my total nightmare where I even went to A&E

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Basically, it seems that for some women, estrogen - starting it or increasing it - can cause heart palpitations, anxiety, jitters, feeling like you've had 8 Red Bulls and high blood pressure and a fast heart rate. That is what I'm going through anyway. The good news is that, the longer I stay on it, the more it seems to settle although it does still play up at night sometimes.
I can sometimes lie in bed and feel like I'm 'pulsing' against the bed and my heart is beating faster than usual. The palps are different to the ones I had before starting HRT (which were the classic 'skipped beat' palps). These ones are like light flutters which go on for ages and ages - hours. My GP had asked me to take my blood pressure twice a day for a week (because I have white coat syndrome) and my home blood pressure machine kept having the 'irregular pulse' icon coming on every time almost...
When I increased my estrogen, I got this pretty much every night at first and a couple times it lasted until lunch time the next day. (I went to A&E once - my ECG was normal apparently although my BP was v high. 158/something.) Now all this has reduced to perhaps a couple times a week, and the pulsing is much less too.
All this is not because my blood estrogen levels are too high, because they were only 233nmol - so still pretty low. It's just how my body is reacting to the estrogen.
I am not sure if I'm going to need cardiac tests etc, but I'm hoping not! My Newson doctor wasn't at all concerned and said I should increase estrogen vv slowly and remain at each increase for a good 8wks+ before increasing anymore. So I have to cut patches into smaller pieces. I'm currently at 62.5 (which is a 50 patch and half a 25 patch!) and next I'm supposed to do a 50 patch and 3 quarters of a 25 patch(!). I am aiming to get to a 75 patch and then re-test my estrogen levels.
Which is all to say - you could either stick at the 50mcg and see if it settles. In my experience, the worst time (most extreme symptoms happening most often) is the first 2 weeks after the increase. After that it does improve and happens less often until (I hope!) it eventually stops totally. Or you could reduce your increase, so you do a 25 patch and half the other 25 patch instead of a full one...