Among my many past contract jobs was a 2 year stint in the credit card industry. It was interesting to see how the credit card industry really worked.
In particular, I found that according to Federal law, companies such as MasterCard and Visa are not permitted to have information that would permit them to identify the names and addresses of cardholders. Therefore they could not have contacted any customers impacted by security problems.
Banks are the card issuers. They are the ones who could notify cardholders if they chose to, if they knew the numbers of the affected cards. I'm guessing that the banks have that card number information.