Coronary vasodilation and the ensuing myocardial hyperemia following the administration of a provocative stressor is a dynamic process. However, established perfusion methods are confounded by contrast accumulation and lack the temporal resolution to accurately evaluate the process. BOLD CMR is an emerging method for monitoring myocardial perfusion without contrast agents, but the current methods are slow. We developed a non-ECG-gated, free breathing, beat-to-beat, cardiac/respiratory phase-resolved, T2-based BOLD CMR sequence at 3T using a low rank tensor framework to enable highly time-resolved assessment of coronary reactivity. We tested the proposed technique in an animal model with and without coronary disease.