We report here the novel use of scanning ion conductance microscopy (SICM) to produce surface images of embryonic stem cell-derived cardiomyocytes (ESCM) to identify individual contracting cardiomyocytes among different cell types. By measuring amplitude and rhythm we can quantitate contraction of ESCM. This method gives, within the same experiment, an assessment of the number and position of ESCM within the layer of mixed cell types, as well as an accurate measure of the response of individual ESCM. Using different modulators of contraction as examples we showed how SICM could be used for recording their responses. We subsequently demonstrated that this model can be used to investigate the protective effect of antiarrhythmogenic drugs.