At least that seems to be the trend:
"The Iowa Heart Center, which is one of the country’s largest groups of cardiology doctors, is considering a merger with Mercy Medical Center in Des Moines. Dr. Bill Wickemeyer, president of Iowa Heart’s board, said the group’s doctors would continue serving patients at all current locations, including hospitals controlled by Mercy’s rival, Iowa Health-Des Moines. He said his practice wanted to emulate places like the Mayo Clinic and the Cleveland Clinic, where specialists work for a large, up-to-date hospital.If you want to belly-up to the ongoing, tenuous government health care trough, the ever-expanding bureaucratic requisites leave cardiologists with no other choice.
“This model seems to be the most successful as we look around the country,” Wickemeyer said.
Iowa Heart has 54 physicians."