What to expect with dual chemical stress test

Looking for a little help. Have to do the chemical stress test next month. Yes heart attack with 4 stents. Stemi.. Stage 3 with 44 percent. On oxygen also with several meds. My biggest fear is going into a severe breathing issue.. Had the 7 day heart monitor done Yes issues. Just afraid of "NO AIR" during the test. Bad enough even without the test. Trying to stay positive but you know how that works.