Any symptoms from the slow heart beats?
[Bradycardia typically does not cause symptoms until the rate drops below 50 BPM.
When symptomatic, it may cause fatigue, weakness, dizziness, sweating, and at very low rates, fainting.[2]
During sleep, a slow heartbeat with rates around 40–50 BPM is common, and is considered normal. ]
Bradycardia - Wikipedia
I don't recall major muscle weakness being part of PN...maybe after long term PN...
I hope the drs are planning testing to rule in or out other things..