TIMI thrombus grade

TIMI Thrombus Grade

An angiographically evident thrombus can be classified as follows for the purpose of quantitative evaluation in clinical trials and day to day practice if needed [1]:

• Grade 0: no angiographic evidence of thrombus
• Grade 1 (possible thrombus present): reduced contrast density, haziness, irregular lesion contour, or a smooth convex meniscus at the site of total occlusion suggestive but not diagnostic of thrombus
• Grade 2 (small thrombus): definite thrombus, with greatest dimensions  up to 1/2 the vessel diameter
• Grade 3 (moderate thrombus): definite thrombus but with greatest linear dimension >1/2 but <2 vessel diameters
• Grade 4 (large-sized thrombus): definite thrombus, with the largest linear dimension >2 vessel diameters
• Grade 5: total occlusion

Angiographic evidence of thrombus for study purpose is taken as the presence of thrombus grades 2 to 5.

Abbreviation: TIMI: Thrombolysis In Myocardial Infarction (From the landmark TIMI trial [2])

References

1. C M Gibson, J A de Lemos, S A Murphy, S J Marble, C H McCabe, C P Cannon, E M Antman, E Braunwald, TIMI Study Group. Combination therapy with abciximab reduces angiographically evident thrombus in acute myocardial infarction: a TIMI 14 substudy. Circulation. 2001;103:2550-4.
2. TIMI Study Group. The Thrombolysis in Myocardial Infarction (TIMI) trial. Phase I findings. N Engl J Med. 1985 Apr 4;312(14):932-6.