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

Stroke. 2017 Jul;48(7):1895-1900. doi: 10.1161/STROKEAHA.116.016253. Epub 2017 Jun 8.


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 tissue-type 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 large-vessel 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 (ρ=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 (ρ=0.39; P=0.01) compared with intra-arterial therapy (ρ=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.

Clinical trial registration: URL: Unique identifier: NCT01429350.

Keywords: middle cerebral artery; stroke; thrombectomy; thrombosis.

Publication types

  • Comparative Study
  • Randomized Controlled Trial

MeSH terms

  • Aged
  • Aged, 80 and over
  • Brain Ischemia / diagnostic imaging
  • Brain Ischemia / drug therapy
  • Brain Ischemia / surgery
  • Combined Modality Therapy
  • Female
  • Fibrinolytic Agents / administration & dosage
  • Fibrinolytic Agents / pharmacology*
  • Follow-Up Studies
  • Humans
  • Intracranial Thrombosis / diagnostic imaging
  • Intracranial Thrombosis / drug therapy
  • Intracranial Thrombosis / surgery
  • Male
  • Middle Aged
  • Outcome Assessment, Health Care*
  • Stroke* / diagnostic imaging
  • Stroke* / drug therapy
  • Stroke* / surgery
  • Thrombectomy / methods*
  • Time Factors
  • Tissue Plasminogen Activator / administration & dosage
  • Tissue Plasminogen Activator / pharmacology*


  • Fibrinolytic Agents
  • Tissue Plasminogen Activator

Associated data