Hi @ddon, I had a period of much faster resting heart rate starting during AC and peaking during Paclitaxel chemo. My resting heart rate often went up into the nineties. Horrible. I mentioned it to my onco but she said it wasn't related although I read online that both types can cause this side effect. It was very disconcerting. And then one day it just stopped. I exercised the whole time and it didn't seem to affect it.
During that time I had two heart scans due to Herceptin and both were fine, my ejection fraction was unchanged. DM me if you want. Hope yours slows soon too.