Table 1.
The TIMI thrombus burden classificationa.
| Grade | Definition |
|---|---|
| Grade 0 | No angiographic characteristics of thrombus are present. |
| Grade 1 | Possible thrombus is present with such angiographic features (decreased contrast density, haziness of contrast, irregular lesion contour, a smooth convex meniscus at the site of a total occlusion, suggestive, but not firmly diagnostic of thrombus). |
| Grade 2 | Definite thrombus is present with greatest dimension of thrombus (<1/2 vessel diameter). |
| Grade 3 | Definite thrombus appears in multiple angiographic views (greatest dimension from >1/2 to <2 vessel diameters). |
| Grade 4 | Definite large size thrombus is present (greatest dimension > 2 vessel diameters). |
| Grade 5 | Definite complete thrombotic occlusion of a vessel (a convex margin that stains with contrast, persisting for several cardiac cycles); angiographic detection of a grade 5 TIMI thrombus leads to further exploration of the occlusive thrombotic content. Either a PCI guidewire or a small balloon is advanced across the thrombotic total occlusion. Crossing the thrombus results in restoration of antegrade flow in the treated vessel. Consequently, the ensuing coronary angiogram enables restratification of the underlying residual thrombus (final TIMI thrombus grade). |