there are plenty of people who want to go into cardiology who are more interested in practicing than an academic career. even in academic centers, 50% or more of graduates eventually end up in private practice. think about it - if everyone in cardiology fellowship remained in academics, who would be taking care of patients?
that being said, a cardiology fellowship is probably the most competitive IM fellowship to obtain. Given the disparity between applicants and positions, programs must devise a way to differentiate applicants. this is done by the usual parameters: US grad vs DO/IMG/FMG, residency reputation, support from faculty and research background.
can you get into a cardiology program without a solid background in research? the short answer is yes, depending on the definition of 'solid background', which i take to mean first authored articles, multiple projects or, in the extreme case, a PhD, MS or research fellowship. most programs would like you to have an 'academic interest' but these same programs realize that A. it is very difficult to determine which candidates are actually committed to research and B. the majority of their fellows will go into private practice, as mentioned above. community fellowships are probably more realistic in this regard (ie, they realize dedicated research is not integral to becoming a cardiologist) but still use research background as a way to differentiate applicants.
I do know a few applicants from my residency program who had no research background and did obtain cardiology fellowships at fairly good programs, but I was at a well regarded residency program. those applying from programs perceived to be less prestigious have to apply with more on their plate, such as research. see what successful applicants from your program (if you're a resident) had done in terms of research before they applied and plan accordingly.
p diddy