I've routinely use accutase for my work, but I don't have experience with using it with cardiomyocytes. One concern with using any dissociating enzyme is the possibility of surface epitope changes. Have a look at the following article to see if collagenase affects the cell surface marker that you're interested in:

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0105602

I routinely use TrypLE, a gentler version of trypsin, for flow studies of PSC-derived cardiomyocytes. There is an article by Lian et al PNAS 2012 that uses Accutase for same purpose. www.pnas.org/cgi/doi/10.1073/pnas.1200250109.