Caffeine. You should avoid caffeine and beta blockers, just because they interfere with the test.
Coffe tea chocolate. If you have a pharmacological stress test such as adenosine, Dipyridamole or lexiscan, you should avoid coffee, chocolate, tea, "brown" colas and aminophylline- containing medications for 12-24 hours before the test because they contain caffeine, an "antidote' to the test. If you have a treadmill stress test, betablockers should be stopped with the approval of your physician.