Greulich S, et al. - In a patient sample with ST-segment–elevation myocardial infarction (MI), researchers used late gadolinium enhancement cardiac magnetic resonance imaging to visualize time-dependent necrosis (STEMI-SCAR project). Participants were consecutively enrolled and had ST-segment–elevation MI with single-vessel disease, complete occlusion with Thrombolysis in Myocardial Infarction score 0, absence of collateral flow (Rentrop score 0), and symptom onset <12 hours. They determined the area at risk and infarct size, myocardial salvage index, transmurality index, and transmurality grade (0–50%, 51–75%, 76–100%) by using late gadolinium enhancement cardiac magnetic resonance imaging. This study included a total of 164 patients (aged 54±11 years, 80% male). According to the findings, immediate reperfusion is important in MI with no residual antegrade and no collateral flow. A high grade of transmural necrosis was induced by a symptom-to-balloon time of >121 minutes. The time to reperfusion to salvage myocardium was less, compared with that suggested by current guidelines, in this pure ST-segment–elevation MI population.