AA has changed the time of our flight from MIA to ORD in January. The departure shifted by only 6 minutes, but the arrival time has slipped by 21 minutes to 19.00

As a result we now have just 95 minutes between our arrival and our connecting flight on BA to LHR (20:35).

Not being the most agile people now, we are concerned about connecting. We might also have assistance.

Flying business on AA and First on BA - but this makes little difference in the airport.

Would appreciate guidance from the experts here.

Do we need to contact AA (assume I have to call AA in London?) to change flights? We are on AA tickets.