After mitral repair on propranolol 40mg twice a day and in driving job is medic alert bracelet needed to warn of epinephrine not to be used ?

YES: This can precipitate an episode of tachycardia .You are on track my friend . Good question.

Possibly.: If the Propranolol is for headaches, not for rapid arrhythmia, and if ones blood pressure is normal, then, assuming ones mitral valve repair eliminated a valve leak and there is no heart failure, then one should be able to tolerate Epinephrine as well as other normal patients. In that case, a special medic alert bracelet seems unnecessary.