How are you feeling, Candice? If you are feeling faint and dizzy, then yes, you should call your doctor. But as long as you are feeling okay, I wouldn't worry too much. A BP as low as 90 systolic can be fine if the person is feeling asymptomatic.

The thing is, atenolol does work as an antihypertensive as well as to regulate arrhythmias, so it is normal that it would lower your BP to some extent.

I hope it is helping your arrhythmia, and that you are feeling better.