Tolga D. Dittrich, MD

Pirson FAV, Boodt N, Brouwer J, Bruggeman AAE, den Hartog SJ, Goldhoorn R-JB, Langezaal LCM, Staals J, van Zwam WH, van der Leij C, et al., and on behalf of the MR CLEAN Registry Investigators. Endovascular Treatment for Posterior Circulation Stroke in Routine Clinical Practice: Results of the Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands Registry. Stroke. 2021.

In contrast to anterior circulation stroke, the evidence for endovascular treatment (EVT) of posterior circulation stroke remains low. In practice, this means that clinicians still face uncertainties regarding the benefit of EVT, with the decision often based on the individual assessment of the treating physician.

In their observational study, Pirson and colleagues compared outcomes of patients who received EVT outside of the BASICS trial at study centers with those from non-study centers. Of 264 patients included, the majority (77%) had basilar artery involvement, with 51% receiving intravenous thrombolysis. A modified Rankin Scale score of 0 to 3 was achieved by 46% (115/252), and 43% (109/252) of patients died. Successful reperfusion was established in 75% (178/238), and symptomatic intracranial hemorrhage was rare, totaling 3% (9/264). Functional outcome was comparable between BASICS study centers and non-study centers (cOR: 0.77 [95%CI, 0.5-1.2]).

Recanalization rates in the present study were slightly higher than in the EVT groups of the BASICS (72%) and the BEST trial (71%).1,2 It should be noted, however, that the expanded TICI (eTICI) used in the present study to distinguish between complete and incomplete recanalization (along with the mTICI from which it was derived) was not primarily designed for posterior circulation and has lower interrater reliability than for the anterior circulation.3

Strengths of this study include the use of recent data from clinical practice with prospectively collected outcome information. Arguably, one of the most significant limitations (in addition to the observational design) is the missing information on treatment selection, given the lack of data on patients who did not receive EVT. Despite these limitations, the present study demonstrates two important points: First, successful reperfusion with EVT in posterior circulation strokes can be achieved in clinical practice, and second, it confirms that posterior circulation strokes are associated with high overall morbidity and mortality.

The pivotal question remains: Does successful recanalization translate into a functional advantage compared with best medical treatment alone (BMT; including IV thrombolysis)? The BASICS and BEST trials both concluded that there was no difference between EVT and BMT in terms of favorable functional outcome.1,2 However, both trials were underpowered due to unexpectedly poor recruitment. Future, more extensive randomized trials are urgently needed to address the question of the efficacy of EVT in patients with posterior circulation stroke.

References:

  1. Langezaal LCM, van der Hoeven EJRJ, Mont’Alverne FJA, et al. Endovascular Therapy for Stroke Due to Basilar-Artery Occlusion. N Engl J Med. 2021;384(20):1910-1920. doi:10.1056/NEJMoa2030297
  2. Liu X, Dai Q, Ye R, et al. Endovascular treatment versus standard medical treatment for vertebrobasilar artery occlusion (BEST): an open-label, randomized controlled trial. Lancet Neurol. 2020;19(2):115-122. doi:10.1016/S1474-4422(19)30395-3
  3. Behme D, Tsogkas I, Colla R, et al. Validation of the extended thrombolysis in cerebral infarction score in a real world cohort. PLoS One. 2019;14(1):e0210334. Published 2019 Jan 10. doi:10.1371/journal.pone.0210334