Impact of Thrombus Length on Outcomes After Intra-Arterial Aspiration Thrombectomy in the THERAPY Trial

Albert J. Yoo*, Pooja Khatri, J. Mocco, Osama O. Zaidat, Rishi Gupta, Donald Frei, Demetrius Lopes, Harish Shownkeen, Olvert A. Berkhemer, Denise Meyer, Susana S. Hak, Sophia S. Kuo, Hope Buell, Arani Bose, Siu Po Sit, THERAPY Trial Investigators, Wim van Zwam, Rdiger von Kummer

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


Background and Purpose-Increasing thrombus length (TL) impedes recanalization after intravenous (IV) thrombolysis. We sought to determine whether the clinical benefit of aspiration thrombectomy relative to IV r-tPA (recombinant tissuetype plasminogen activator) may be greater at longer TL.

Methods-THERAPY was a randomized trial of aspiration thrombectomy plus IV r-tPA versus IV r-tPA alone in largevessel stroke patients with prospective TL measurement >= 8 mm. In this post hoc study, we evaluated the association of TL with trial end points and potential endovascular treatment effect, using univariate, multivariable, and multiplicative interaction analyses.

Results-TL data were available for all 108 patients (28% internal carotid artery, 62% M1, and 10% M2). Median TL was 14.0 mm (interquartile range, 9.7-19.5 mm). Longer TL was associated with worse outcome (90-day modified Rankin Scale score: odds ratio, 1.24 per 5-mm TL increment; 95% confidence interval, 1.04-1.52; P=0.02), even after adjusting for key outcome predictors (adjusted P=0.004). Longer TL was also associated with more serious adverse events (adjusted P=0.01), more symptomatic hemorrhages (adjusted P=0.03), and increased mortality (adjusted P=0.01). No significant relationship was observed between TL and angiographic reperfusion (modified thrombolysis in cerebral ischemia 2b-3), but greater TL was associated with longer endovascular procedural times (rho=0.36; P=0.045). Increasing TL was associated with greater aspiration thrombectomy treatment effect (interaction term P=0.03). This might be related to a potentially stronger adverse effect of increasing TL on 90-day modified Rankin Scale for patients treated with IV r-tPA (rho=0.39; P=0.01) compared with intra-arterial therapy (rho=0.20; P=0.165).

Conclusions-Ischemic stroke patients with longer symptomatic thrombi have worse 90-day clinical outcomes but may have a greater relative benefit of aspiration thrombectomy over IV r-tPA alone.

Original languageEnglish
Pages (from-to)1895-1900
Number of pages6
Issue number7
Publication statusPublished - Jul 2017


  • middle cerebral artery
  • stroke
  • thrombectomy
  • thrombosis

Cite this