Lack of detailed data requires a conservative approach in the IEC 60601-2-33 safety limits to prevent cardiac stimulation (CS) by MRI gradient switching. Analogous to our previous peripheral nerve stimulation modeling, we use coupled electromagnetic and electrophysiological simulations to investigate magnetically induced CS in human and canine body models. Our CS simulation pipeline reproduces CS thresholds measured in previous dog experiments. The predicted human CS thresholds are significantly higher than the regulatory safety limits. With further validation, CS simulations could eventually play an important role in determining appropriate MRI safety limits.