| Grade 0 - Complete occlusion of the infarct-related artery |
| Grade 1 - Some penetration of contrast material beyond the point of obstruction but without perfusion of the distal coronary bed |
| Grade 2 - Perfusion of the entire infarct vessel into the distal bed but with delayed flow compared with a normal artery |
| Grade 3 - Full perfusion of the infarct vessel with normal flow |
