I Have Been Experiencing Palpatations, Pvc's And Pac's For Which

I have been experiencing palpatations, pvc's and pac's for which i have been taking metoprolol 25mg bid. (I also have hx of brief spurts of svt.)I have recently begun having more irregularity in heart rhythm with brief pauses and periods where my pulse seems to get "weak". I have a pulse ox & the wave forms seem to be almost nonexistent at times even though i can still feel a pulse & the pulse ox reads out a heart rate usually in the low 60's which is a normal rate for me. During those times other than "fluttering feeling" in my chest i am asymptomatic with the exception of extreme fatigue. I do have moderate obstructive & central sleep apnea. I use my cpap faithfully & just had a sleep study to determine settings. Your advise please