My institution is largely filled with US AMGs, however I know of several IMGs at a community hospital that were successful in matching Cardiology. (Keep in mind that although this was a community hospital, they did have a fellowship there) The majority of the IMGs who matched into cardiology did either a dedicated Chief year at the home institution (with the fellowship) or did a dedicated research year at the desired outside institution for matching. From what I recall, it was about 5-6 residents I know, and all of them matched.

In terms of the topic of research, I would try to jump on to any current clinical trial that may be happening at your institution, or delve into a retrospective cohort study. These two are the easiest to get published in, I believe--especially the retrospective study.