How can we distinguish 'stunned' from 'hibernating' myocardium?

Time: Stunned myocardium implies a short-term injury to the heart resulting in decreased function of the heart which recovers in 10-14 days. Hibernating myocardium implies a chronically decreased blood supply to the heart which results in poor heart function. Unlike stunned myocardium, the heart function in hibernating myocardium will not improve until the blood supply is repaired.

Excellent question: Stunned usually refers to reduced ejection fraction in the setting of normal perfusion, i.e., takotsubo, stress induced cmp, which usually recover rapidly. Hybernating usually refers to ischemic myocardium with reduced lv function.., i.e., patients with CAD who have iw hypokinesis with reduced initial perfusion on stress imaging though with recovery of perfusion noted on delayed viability.