Don't throw away your STL-MIA ticket ! it's gold. Since they did slightly change the schedule you comply with the change rules (more than 31mn OR "
unless the schedule change results in a "misconnect".):
http://www.aa.com/i18n/agency/Bookin...e_240_80.jsp#1
You both match AA schedule change and other airline schedule change... You stay within the oneworld alliance... they probably sort out something for you.