| Pressure index | State of vessels |
| >1.2 | Rigid or calcified vessels or both |
| >1 | Normal (or calcified) |
| <0.9 | Ischaemia |
| <0.6 | Severe ischaemia |
| Pressure index | State of vessels |
| >1.2 | Rigid or calcified vessels or both |
| >1 | Normal (or calcified) |
| <0.9 | Ischaemia |
| <0.6 | Severe ischaemia |