I too have had POTS, functional for several years now but 2 days ago my HR was 47. It felt like my chest wasn't getting perfused, strange feeling. After years of pointless ER visits I don't go anymore. I ate a bunch of food, did some squats and it got higher then I took a nap. Beens low 60s since. My resting HR is mid to low 50s lately and it just feels a bit low but I deal.