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. 2019 Jan;21(1):91-100.
doi: 10.5853/jos.2018.01921. Epub 2019 Jan 31.

Does Clot Burden Score on Baseline T2*-MRI Impact Clinical Outcome in Acute Ischemic Stroke Treated with Mechanical Thrombectomy?

Imad Derraz  1 , Romain Bourcier  2 , Marc Soudant  3 , Sébastien Soize  4 , Wagih Ben Hassen  5 , Gabriella Hossu  6 , Frederic Clarencon  7 , Anne Laure Derelle  1 , Marie Tisserand  8 , Helene Raoult  9 , Laurence Legrand  5 , Serge Bracard  1 , Catherine Oppenheim  5 , Olivier Naggara  5 ; THRACE Investigators  1
Collaborators, Affiliations

Does Clot Burden Score on Baseline T2*-MRI Impact Clinical Outcome in Acute Ischemic Stroke Treated with Mechanical Thrombectomy?

Imad Derraz et al. J Stroke. 2019 Jan.

Abstract

Background and purpose: A long clot, defined by a low (0-6) clot burden score (CBS) assessed by T2*-MR sequence, is associated with worse clinical outcome after intravenous thrombolysis (IVT) for acute ischemic stroke than is a small clot (CBS, 7-10). The added benefit of mechanical thrombectomy (MT) might be higher in patients with long clot. The aim of this pre-specified post hoc analysis of the THRombectomie des Artères CErebrales (THRACE) trial was to assess the association between T2*-CBS, successful recanalization and clinical outcome.

Methods: Of 414 patients randomized in the THRACE trial, 281 patients were included in this analysis. Associations between T2*-CBS and clinical outcome on the modified Rankin Scale (mRS) at 3 months were tested.

Results: High T2*-CBS, i.e., small clot, was associated with a shift toward better outcome on the mRS; proportional odds ratio (POR) per point CBS was 1.19 (95% confidence interval [CI], 1.05 to 1.34) in the whole population, 1.34 (95% CI, 1.13 to 1.59) in IVT group, and 1.04 (95% CI, 0.87 to 1.23) in IVTMT group. After adjustment for baseline prognostic variables, the effect of the full scale T2*-CBS was not statistically significant in the whole population and for the IVTMT group but remains significant for the IVT group (POR, 1.32; 95% CI, 1.11 to 1.58).

Conclusion: s A small clot, as assessed using T2*-CBS, is associated with improved outcome and may be used as a prognostic marker. Despite the worst outcome with long clot, the relative benefit of MT over IVT seemed to increase with low T2*-CBS and longer clot.

Keywords: Endovascular recanalization; Ischemic stroke; Magnetic resonance imaging; Thrombosis.

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Figures

Figure 1.
Figure 1.
The T2*-clot burden score (T2*-CBS). (A) A score of 10 is normal, implying absence of susceptibility vessel sign (SVS) on T2*. Three points (as indicated) are subtracted for SVS found in the supraclinoid internal carotid artery (ICA), 2 points for SVS in each of the proximal and distal halves of the middle cerebral artery trunk (M1), 1 point for SVS in the A1–A4 segment and 2 points for SVS in the M2–M4 branches. A score of 0 implying complete multisegment vessel occlusion. (B) Patient 1, distal occlusion with T2*-CBS=9 (SVS in 1 left M2 branch). (C, D) Patient 2, proximal occlusion with T2*-CBS=3 (SVS in right supraclinoid ICA, proximal and distal halves of M1).
Figure 2.
Figure 2.
Flow chart study. CT, computerized tomography; MRI, magnetic resonance imaging; CBS indicates clot burden score; mRS, modified Rankin Scale; IVT, intravenous thrombolysis; IVTMT, intravenous thrombolysis mechanical thrombectomy.
Figure 3.
Figure 3.
Modified Rankin Scale distribution for the intra-arterial treatment and control arms for T2*-CBS groups (0–6) and (7–10). CBS, clot burden score; IVT, intravenous thrombolysis; and IVTMT, intravenous thrombolysis mechanical thrombectomy.
See this image and copyright information in PMC

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