Have you taken Xanax with Zoloft before?? I'd ask a pharmacist if you can take it, or your doctor. THAT I wouldn't know about.
But if you could, Xanax is great! I use it as needed and have done so for years. At one point I was taking .25 twice a day for 4 months (horrible worrying), then stopped for months and have taken it just as needed. (maybe 3 days in a row at night, then not for a week, then another night, then not for 2 weeks, and so on) But if you are only taking it because of a heart rate being in the 80's then that's not even necessary because resting heart rates between 60-100 are normal.