Catholic Health East in Newtown Square has agreed to merge with Trinity Health in Michigan to form a system that would include 82 hospitals in 21 states coast-to-coast, the two Catholic health providers said Wednesday.

The deal is far from complete. The two systems, which together have more than $13 billion in annual revenue, said they signed a nonbinding letter of intent to join forces. The goal is to reach a definitive agreement in the spring of next year

The board agreed that John R. Swedish, president and chief executive of Trinity, which is based in Novi, Mich., will retain those positions if the merger is completed.

Judith M. Persichilli, president and chief executive of Catholic Health East, whose holdings in the Philadelphia region include the Mercy Health System in Pennsylvania and the Lourdes Health System in New Jersey, will become executive vice president of the new organization.

Terms of the proposed deal were not disclosed.

It's not clear what the deal means for Catholic Health's headquarters in Delaware County.