Cardiac magnetic resonance elastography (MRE) promises a quantitative mapping of the mechanical function of the myocardium. However, the implementation of cardiac MRE is challenging due to fast motion, high heterogeneity and temporally varying intrinsic properties of the heart. To overcome these limitations, we introduce a novel cardiac MRE sequence with spiral readout, respiratory navigator and stroboscopic wave sampling. It allows acquiring 100 wave fields with 45ms temporal resolution, 1.6x1.6mm² in-plane resolution at three frequencies within 9 minutes. Preliminary data in 8 healthy volunteers show a substantial variation of myocardial shear-wave velocity from 1.5±0.2m/s during diastole to 2.1±0.2m/s during systole.