Ivabradine here, 2.5mg twice daily, with a third dose on occasion if I've been busy and feel symptomatic. Works way better for me than beta-blocker.
I've also noticed quite an improvement from taking Cetirizine, 10mg twice daily. My POTS is strongly hyperadrenergic with suspicion of Mast Cell Activation playing a part, so it makes sense.
Circadin also seems to help with the sleep disruption that POTS can cause too.