We have a CCM only program; 6 spots per year, total complement of 12... which is pretty big for a CCM-only program.
The reason that there aren't many CCM-only programs relative to the total number of PCCM programs has to do with a requirement of the ACGME for CCM program accreditation.
For an institution to apply to have a CCM fellowship, they already have to have an IM residency in place, as well as 3 other IM subspecialty fellowship programs. CCM is the only IM fellowship that has an accreditation requirement dependent on the presence of other fellowships. Now, pulmonary counts as one of those IM subspecialty programs you can have, and as a twist, if your institution only has two IM fellowships in place, you could apply for pulm and CCM combined at the same time.
That strict requirement is starting to loosen so I would expect to see a rise in CCM-only programs in the next few years.
Now, as for what you should apply for... pulm only, or CCM only, or PCCM... it's the age-old advice of "train in the field you want to practice in". If your plan is to do CCM only, then just do CCM. You will spend more time in the ICU as a CCM fellow than you will as a PCCM fellow. And if you want to have a clinic and never set foot in an ICU, then pulm alone is better than the combined track. PCCM is good if you want to do both (and not have one as a fallback 10 years down the road... if you don't practice in one for a decade then you aren't going to be able to pick it back up way down the road as a "retirement option") or if you want to do research.
If your goal is to do PCCM, my 2 cents is that it's better to not match into a combined program, than to try and do them piecemeal. While most CCM programs have a mechanism in place to accomodate someone who only needs to do 1 year, it messes up the acceptance plans. If I accept a 1yr person this year, then I have to accept another 1yr person next year or have an unfilled spot in the program. And maybe next year there won't be a good 1yr applicant. Personally, it doesn't factor into our point-structure for applicant ranking, but it does whisper in the back of our minds.
That's a lot of words that ultimately boils down to: it depends