Wow, bold letters.
Lydia had her heart open THEN she heard what Paul had to say. (Did you like my big bold capatilized THEN ?)
What Paul said didn't open her heart...God did.
That's not what it says. Read it again.
14 A woman named Lydia, from the city of Thyatira, a seller of purple fabrics, a worshiper of God, was listening and the Lord opened her heart to respond to the things spoken by Paul.