Oh no. It may be the height. Mexico city is 2,240 meters over sea level. Might be hard for a heart that is not used to it.

I believe this is how my grand mother died. She fainted at the airport when they arrived to Mexico city. She was discharged and then in the morning she woke up for a few minutes, exchanged a few words with my Mom, it was my Moms birthday, closed her eyes and died. She came from a small city at only 1,600 mt, my grand father had died just 6 days before after a long struggle with cancer. So member of the family think it was my grand father that came for her. But I think it was the elevation and her heart.