I was told by someone that combined 5 year IM/card residencies exist but have not been able to locate where. If anyone has any ideas, they would be much appreciated.
I am unaware of any current combined IM/Cardiology training.
There is the ABIM research pathway, where you do 2 years of Internal Medicine Residency, then proceed to the subspecialty field (cards, GI, nephro). But you don't save any time - that extra time has to be dedicated to research so the start and finish time is the same if you did ABIM research pathway for IM/Cards, or if you did IM then cards fellowship. You'll just have more research experience/publications in the research pathways (which makes you more competitive for academic medicine, pharmaceutical research, perhaps government FDA/DEA/NIH, etc)