Interesting threads and ambitions. Perhaps I need some clarification...would you like to work in a hospital setting in cardiac rehab, or more of a physio-rehab setting such as a physical therapist or athletic trainer? The fields are miles apart.
If indeed you'd like to go into cardiac rehab, any Master's program with a clinical exercise physiology focus can fulfill your needs. Coursework should include EKG interpretation, advanced exercise prescription, advanced exercise prescription, and topical course like Exercise and Aging or Exercise and Chronic Disease states. Cardiac rehab professionals have an exercise science background, can read and interpret EKGs (ECG, same thing), and gain practical experience through practicums and internships with actual hospital programs.
Regarding finding programs, there are dozens out there, so with all due respect your search methods might not have been the best. Many Master's programs with "Exercise Physiology" or "Clinical Exercise Physiology" wil adequately prepare you, and internships will open doors. My alma mater, Ball State University (Muncie, IN) has a phenomical Clinical ExPhys program with required hours in the hospital and prepares students to work in a clinical settings.
Finally, regarding ACSM certs, you'll be looking for the Exercise Specialist or Registered Clinical Exercise Physiologist certs.