Alejandro Rodríguez-Vázquez, MD

Pfaff JAR, Schönenberger S, Herweh C, Ulfert C, Nagel S, Ringleb PA, Bendszus M, Möhlenbruch MA. Direct Transfer to Angio-Suite Versus Computed Tomography–Transit in Patients Receiving Mechanical Thrombectomy: A Randomized Trial. Stroke. 2020;51:2630–2638.

Time is one of the most important elements when it comes to determining the efficacy of mechanical thrombectomy (MT) in acute stroke. The usual pathway across specialized stroke centers for initial evaluation of patients with suspected stroke includes a stop for neuroimaging like a multimodal-CT after the first clinical examination and before treatment. On the other hand, stroke imaging could be acquired directly in the angio-suite via flat-panel CT. There are some articles which defend this method as a faster and better way in terms of outcome to proceed with MT. However, this was not the subject of a clinical trial until now.

This was a prospective, single-center, parallel-group, open-label investigator initiated randomized trial in which the authors compare workflow metrics according to a CT-transit (CTT) pathway versus a direct transfer to the angio-suite (DTAS) pathway before MT. Both pathways include a non-contrast CT and a CT-angiography, plus a perfusion-CT (CTT) or a parenchymal blood volume imaging (DTAS) when presenting after 4.5 hours of symptom onset. The primary outcome of the study was time from stroke imaging to groin puncture. Other workflow metrics like admission to imaging or imaging to reperfusion time were also assessed, as well as final reperfusion and clinical outcome. The study included patients with an acute stroke secondary to a large vessel occlusion of the carotid territory with a National Institutes of Health Stroke Scale >7 and modified Rankin Scale 0-3 which undergo MT after a complete evaluation. In addition, intravenous thrombolysis (IVT) was performed if treatment criteria were fulfilled. Patients which required intubation between neuroimaging and groin puncture were excluded in order to minimize the mode of sedation bias. Wake-up strokes were also excluded because MRI was the preferred imaging method.

Although a total number of 110 patients was estimated, the trial was stopped after a pre-planned interim analysis performed after 60 patients were recruited (34 CTT and 26 DTAS). The primary outcome was favorable to DTAS with a 7-minute reduction in imaging to groin puncture time (19 vs 26 minutes). However, in the DTAS group, admission to imaging time was longer (21 vs 12 minutes), so the time to reperfusion was finally balanced. This initial delay, as well as a lesser sensitivity of early ischemic changes in the DTAS imaging, which could lead to an under-use of IVT, was the main reason to stop the trial without reaching the scheduled number of patients. Besides, final angiographic results were better in the CTT group, although the imaging modality by itself is unclear in its effect on the reperfusion results. Conversely, clinical outcome after three months was comparable in both groups.

The results of this study, therefore, do not fit with the ones showed in previous publications which suggested DTAS pathway as a faster and better approach to MT. This could be explained because, in those articles, many patients received stroke imaging before arriving at the MT center and thus were not enrolled in-house as they were in the present clinical trial. The latter suggests that DTAS could be the pathway of choice when certain requisites are fulfilled, leaving the CTT pathway a better choice (?) for patients without a previous evaluation. In addition, this study does not include wake-up strokes because MRI was preferred over CT, and this is a large group of patients who could benefit from a faster but still reliable approach. Moreover, there are many local conditions such as the distance between the CT and the angio-suite or the presence or not of the neurointerventionist which could affect the workflow and thus the generalizability of the results of this trial. As faster and more precise neuroimaging techniques are developing, work pathways should evolve and be adapted to their community’s needs — time is brain!