You need a sleep study. I don't think your pacemaker will do anything for sleep apnea. Untreated, it can cause all kinds of problems, like hypertension and my doctor is convinced that it was a contributing factor to my afib.
your PM should stop your heart from going below the set amount they have for you - say 40 bpm, but it will not do anything for your sleep apnea other than pace your heart to that rate; as far as I know with my limited knowledge as a patient
I have moderate OSA (1 pt from severe) and a PM/ICD and I still suffer some from episodes; but not often like I used to - I would def discuss with your dr about a sleep study and use a cpap or other treatment if you haven't already (I'm set at 50 bpm even at night due to ANS problems)