Abstract BACKGROUND: The Wellens' electrocardiogram (ECG) pattern of dynamic T-wave inversion in the anterior leads is observed in clinical conditions characterized by reversible left ventricular (LV) dysfunction (stunned myocardium), either ischemic or nonischemic. The pathophysiologic basis of this ECG pattern remains to be elucidated. OBJECTIVE: The purpose of this study was to report the contrast-enhanced cardiac magnetic resonance (CE-CMR) findings in 4 cases of Wellens' ECG pattern associated with transient LV dysfunction from a variety of clinical conditions such as myocardial bridge, coronary artery dissection, cholecystitis, and takotsubo syndrome. METHODS: All patients underwent CE-CMR at the time of acute clinical manifestations and after 6 to 8 weeks of follow-up to assess the presence and dynamics of LV myocardial changes. RESULTS: In all patients, the Wellens' ECG abnormalities were associated with increased signal intensity of the LV myocardium on T2-weighted sequences suggesting myocardial edema, in the absence of late enhancement on postcontrast sequences. Repolarization abnormalities and myocardial edema had a parallel time course with persistence beyond recovery of mechanical abnormalities. T-wave inversion was associated with transient prolongation of the QTc interval in all cases. CONCLUSION: The study results suggest that myocardial edema rather than systolic dysfunction underlies the Wellens' ECG pattern, regardless of the causative mechanism