So get it checked laying down? If it is enough that you can feel, be sure to mention that to your Dr.
the weird thing is, i can hear it in my ears and feel it in my chest when i lay down at night, but it doesn't show up when the nurse takes my pulse in the office. it only seems to happen occasionally, not consistently, and it never happens while in the dr's office.
That is so odd - I had a doctor appointment a couple of weeks ago and I was also told I had an irregular heart beat - never did before the painkillers. I don't know if it will get better..... Sorry I couldn't answer your question.
How long have you been clean? I don't know anything about Methadone but I've been clean a year off Lortabs and I think my heartbeat can be irregular at times from all the drugs. I would have it checked if I were you. Mine always checks out fine but you know when it's beating too fast or something isn't right. When I was going through WD it went crazy for weeks or more.
I have the same thing and I was diagnosed after I was years into the pain meds. It was never determined if that was the cause because it it hereditary and my mom had it. I now take daily meds for it and they do help.
I would get it checked out. Too many things it could be. You need to know for sure.