In answer to the question can heat cause one to pass out, I can state in the affirmative, but with a cadre of medical personnel, and others about her she would have been appropriately prepared for such heat as is required to cause such an event.
Certain precautions would have made this situation a non happening. Appropriate dress. Salt pills. Hydration. Other means addressed by appropriately licensed medical professionals such as are on tour with her.
Isn’t it amazing she’s the only one reported to have passed out due the heat?
Just about everything that was going to kill you a year ago is good for you, and vice versa. I'm sort of waiting to be able to start smoking again.