As long as there are no dropped beats, passing out ( syncope) or lightheadedness then a slow heart rate is simply a marker of longevity. Rarely this can be a marker of underlying conduction system disease, but if your resting EKG is normal then this is unlikely.
There are many medications which may cause this, but once again if there are no symptoms then there is no need to worry.
I also have "bradycardia" with a resting HR of 48. My BP is also lower, in the 96/54 range. I have attributed mine to being a cyclist and runner, altho that has never been quantified. In terms of sleep apnea, I do not know if that would be the cause. If you have had the apnea for awhile, then I would be hesitant to link the 2 since it sounds like your HR just recently dropped. Your attempt to stop smoking (congrats!) might be a better link, because from what I know your HR will lower when you stop the nicotine. In fact, I have read that the drop in BP and HR happen within 20 minutes of stopping!! I am not a doctor tho, so I can't say for sure :)
Good luck!!
from what i was told a slow heart rate is a good thing, well not in hte 30's. my Hr sometimes goesin the 40's. I had all of those test. I remember the doctor asking me if I jogged or things like that. they say people who "workout" can have a slower HR.
I hope all is well and good luck
Michelle
i have a slow heart rate to my cardio dr says its good not to worry about it mine runs between 49-79 ,