We propose a three-compartment model to perform cytometry in cardiac diffusion MRI. Our approach adapts the VERDICT model to account for the anisotropic geometry of cardiomyocytes. The model was fit to data from ex-vivo mouse heart imaged with multiple diffusion times, diffusion directions, and q-shells. The model yields realistic volume fractions (intracellular/extracellular/vascular = 68/16/16%) and cell radii (7-9.5 μm). The parameters derived could aid quantitative characterisation of cardiomyopathies including hypertrophy and fibrosis.