After a woman orgasm, Both breathing and heart rate will increase. As a result of the excitement of the central nervous system, the result is increased breathing and heart rate. At orgasm, the number of breaths can reach 40 times / min, the heart rate increases to 120 times / min, and some women even up to 150-160 times / min.
Well fear of heart issues certainly ruins the moment, doesn't it. I think the other poster was trying to say that even under normal circumstances, the heart rate will change and even blood pressure.
So, POTS is often caused by certain things like even anemia, diabetes, etc. Have they determined any reason why you have POTS? And do you do anything about it such as medication, lifestyle, diet, exercise, etc?
I'm wondering about the outcome of your doctor's appointment. What was the recommendation. I'd say the best thing is to either wear a holter monitor if you feel this would recur in a 24 hour period or an event monitor if you need more time to have the situation occur.
Cardiac issues during sex are not uncommon unfortunately.