Been there, done that.
Ironically, it was a colonoscopy that revealed my atrial fibrilation. They were taking my vitals prior to the procedure, and the nurse asked me, "Are you nervous?" And I wasn't, because I'd undergone a colonoscopy before, and I knew the worst of it was behind me (see what I did there?). But she said my heart rate was, like 144 bpm.
They gave me some medicine to lower my heart rate so they could do the procedure, but when I came out of it, they checked me again, and my bpm was racing. So they sent me to the ER, and ultimately discovered my condition. Got that sorted out, and I'm doing well now.
Anyway, I hope your procedure takes care of anything suspicious. Early detection is key. Be well, and enjoy a good, hearty meal when it's all over.