I have had a lot of patients ask about this. The problem with HR monitors and A-Fib is that your rate is constantly changing, so the monitor is only going to show you trends up or down over time, as the rate is not going to ever stay the same. You may be lucky and have a ventricular response rate that is reasonably "tight," meaning it only ranges 10-20 beats per minute difference in conduction time on average, but, you won't know until you try. If your baseline ventricular rate jumps around from the 50's to the 90's, the monitor is going to be jumping all over the place. In the hospital, we run a strip on an A-Fib patient and give a HR range, not a definite rate.

A strap monitor will work better than the hand-holders at the gym, but whether it will work well enough for you to use and not go insane depends. The bottom line is that you have an irregularly irregular heart-rate. Digoxin (or other medications) may control the ventricular response, but, unless you are in a 2:1 flutter or something, you will always have a number that jumps all over the place on a monitor that is working perfectly.

Good luck.