From Luchawiki

Ron Skoler used the IWC name to promote AAA shows in the United States. The most notable show being When Worlds Collide. When Antonio Pena and Skoler had a falling out, Pena decided to have all the IWC Champions at the time lose their belts to his National champions, thus unifying the belts. The only title not to receive this treatment was the IWC World Heavyweight Title.