I'm undx to date, so anything I tell you may or may not be MS connected. Does anyone know if migraine causes heart palpitations?
Anyway, I've had PACs for years. Last Fall's 24-hour Holter monitor showed several hundred, but almost never more than one beat at a time. Nobody seems concerned about them, but they certainly don't impart a feeling of restfulness and well-being.
I have read about the possibility that MS could fiddle around with one's heart rhythm, but I don't know whether there's much information out there on the topic. Maybe Lulu54 would have a better handle on this question; I know she's had significant heart issues in addition to definite MS.
Shortness of breath while sleeping, for me, only happens when my CPAP mask slips into an awkward position, and blocks my air intake rather than pressurizing it. That is generally more than enough to get me to wake up. With regard to gasping, I haven't been much of a gasper since the good Lord freed me from that nicotine addiction, many years ago. Heavy breathing's another matter; with my middle-aged mid-American midsection, a couple of flights of stairs can get me to huff & puff a little bit.