I posted an update to my tread on "living with AFib", that touches on this subject.
I post here as I would like to draw specific attention to the difference I have learned mostly by the help of other patients who contribute to this Community and from web searches. Strangely, in my mind, my Cardiologist never volunteered consideration of Atenolol even though I have complained to him for years (at least 10) that I suffer from dream problems, I call them trouble mares. That is a subject for the "sleep disorders" Community to which I also contribute - so I'll I will not go into more detail here on that subject.
Following are my observations on day two of substituting Atenolol 25 mg twice a day for Metoprolol 25 mg twice a day.. both are regular, for Metoprolol it is called Tartrate, I think the Atenolol comes in only one normally longer lasting form.
Today in the early afternoon, following my third 25 mg dose of Atenolol at about 9 AM, I noticed some dizziness when I rose from a time sitting. This is not unusual for me, but I checked my HR anyway (using my new Oximeter, subject of another post) and found even though I was then on my feet and had walked at least 10 feet my HR was in the mid 50s. Prior to changing to Atenolol I rarely saw my resting HR below the low 70s. I also note my resting HR yesterday and in the early hours of this morning were mostly 70s for resting, some 60s.
I then went outside and did some physical work, spitting some Ash Hardwood for firewood. Most of this splitting was done with a 4 ton electric splitter for which I had only to lift the rounds (upwards of 40 pounds I estimate) onto the splitter and then pull them splits apart and throw on a stack. This went on for perhaps 40 minutes with me having to revert to an 8 pound maul (sledge hammer) and Wedge to split some rounds that stopped the light duty electric splitter. I estimate I made no more than 30 swings with the heavy maul. This fairly strenuous exercise did make me a bit breathless and I found my HR only in the upper 90s. Before Atenolol I recall a similar workout would have put my HR over 130, or near my maximum allowed rate.
Research on the web says that Atenolol is much longer lasting than Metoprolol and suggests that Metoprolol Tartrate has to be taken twice a day... Atenolol only once ! Strangle, again, my Cardiologist who issued a prescription for Atenolol upon my request to be allowed to try it is for 25 mg twice a day.
Given my unusual low HR I conclude that taking the Atenolol twice a day would be more comparable to taking the Metoprolol (same 25 mg) Slow Release twice a day - thus being equivalent to an increase in BB level, thus the lower HR.
I plan to skip my bedtime does, treating my morning Atenolol as a long lasting once a day. This will also cut my intake of BB from 50 mg a day to 25 mg. I will keep a close watch on my HR and be sensitive to any unusual heart symptoms, the current unusual low HR going back to upper 60s or lower 70s at rest being considered normal, not unusual. I look to with some hope that the reduced dose coupled with the lower brain side-effect of Atenolol will reduce the problem dreaming. I fully expect to wake up in the early AM hours and will check my HR then, I keep my Oximeter (with HR meter) on my nightstand.