The Source for Neurovascular News and Education

July 14, 2024

From the outset, choose the approach that is the most likely to be successful, a study author recommends.


Patients undergoing mechanical thrombectomy for large-vessel occlusion tend to have poorer functional outcomes if their cases involved a higher number of passes, according to a single-center observational analysis published online June 10, 2019, ahead of print in Stroke.  


“Previous studies suggested that there is a first-pass effect in relation to thrombectomy,” senior author Marc Ribo, MD, PhD (Hospital Vall d’Hebron, Universitat Autònoma de Barcelona, Spain), told Neurovascular Exchange in an email. “We aimed to study if there is an additional detrimental effect for each added pass. Moreover, we wanted to determine if there is a number of passes above which it is not worthwhile to keep trying to achieve recanalization.”


Researchers led by Álvaro García-Tornel, MD (Hospital Vall d’Hebron, Universitat Autònoma de Barcelona, Spain), retrospectively evaluated data on 542 consecutive patients who underwent mechanical thrombectomy for LVO of the anterior circulation at a single tertiary stroke center from 2012 onward. They noted patients’ baseline characteristics, number of passes, recanalization degree, clinical outcome at 24 hours, and functional outcome at 90 days.


Overall, 84% of patients achieved successful recanalization, defined as an mTICI 2b-3. Of these patients, 39% achieved successful recanalization after a single device pass.


Multivariate analysis revealed that first-pass recanalization and an mTICI of 3 were independent predictors of both good functional outcome (90-day mRS ≤ 2) and dramatic clinical recovery (final NIHSS score ≤ 2 or a decrease of ≥ 8 points in 24 hours).


Independent Predictors of Outcome and Recovery: OR (95% CI)


Good Functional Outcome

Dramatic Clinical Recovery

First-Pass Recanalization

2.5 (1.4-4.5)

1.8 (1.1-3)


2.6 (1.5-4.7)

2.9 (1.75.1)


The rate of recanalization declined after each pass, from 39% with one pass to 35% with two passes, 33% with three passes, 24% with four passes, and 28% with more than four passes (P < 0.001).


Among patients who achieved recanalization, there was a linear association between number of passes and good functional outcome, with 58.6%, 50.5%, 48.4%, 38.5%, and 25.6% for one, two, three, four, and more than four passes, respectively. By comparison, 16.9% of patients who didn’t achieve revascularization had good functional outcome.


Go ‘All-In’ With First Pass


“Our findings confirm that each additional pass reduces the chances of recovery,” noted Ribo. “However, our observations suggest that recanalizing after up to four to five attempts is still associated with better outcome than no recanalization.”


He explained that several factors could be behind the worse outcome with more passes. “First and most obvious is that additional passes mean longer occlusion time, and this is clearly related with worse outcome,” Ribo observed. “Second, more interactions with the clots lead to higher fragmentation of particles that may embolize to distal arteries. Third, we know form in vitro studies that squeezing and dragging the clot reduces its water content and leads to higher friction and adhesion of the smashed clot. Also, there is certainly direct damage to the vessel wall for each additional pass.”


Based on these findings, Ribo recommended that “neurointerventionalists should ‘throw in’ the best that they have . . . at the first pass and not approach the situation thinking that if the first pass fails, they will have a second chance.”


For instance, if a combination of devices appears most likely to be successful, then this combination should be used from the beginning and not reserved for use after a single device pass is attempted. Similarly, if a stent retriever is not perfectly deployed the first time, the best option is likely to reposition it rather than go for a suboptimal pass.


Unanswered questions, according to Ribo, include how far up distal branches neurointerventionalists should be chasing clot fragments after partial recanalization and when they should consider performing an angioplasty with or without stenting when conventional thrombectomy fails.



García-Tornel Á, Requena M, Rubiera M, et al. When to stop: Detrimental effect of device passes in acute ischemic stroke secondary to large vessel occlusion. Stroke. 2019;Epub ahead of print.




  • García-Tornel reports no relevant conflicts of interest.
  • Ribo reports being a cofounder and shareholder of Anaconda biomed and has served as advisor for Stryker, Medtronic, Cerenovus, Amnis, Perflow, and Apta targets.