Yes. You can do a fourth year in ACHD, although, at the time, it does not seem to be a requisite to become an employable ACHD specialist (vs. say, cath or EP which do require at least a 4th year of training). Many peds cards programs have a strong ACHD component and ACHD patients are predominantly taken care of-for their heart issues-by pediatric cardiologists, unless they develop other more adult cardiac comorbidities. I have seen many adults in my fellowship and have recently been involved with caths or EP studies on a few adults age ranges 20s to early 60s. As of now becoming an ACHD specialist only takes developing that interest in fellowship (though some may push 4th year training as a requisite in the future). Also, people who become imaging, cath, and EP specialists as pediatric cardiogists often see a lot of adults-at least where I am).
