Monitoring the viability of myocardial tissue is of prognostic value after an ischemic event1-3. Ultrahigh fields (B0≥7T) facilitates cardiac 39K MRI. However, short relaxation times, low signal-to-noise ratio, and low spatial resolution render the quantitative determination of the myocardial tissue potassium concentration (mTPC) challenging. We analyze the feasibility of quantitative cardiac 39K MRI at 7T with simulations. For realistic noise conditions the mTPC can be determined with a deviation of 14% from the ground truth by applying a partial volume correction. Quantitative cardiac 39K MRI would further benefit e.g. from higher magnetic field strengths (B0>7T) or iterative reconstruction techniques.