To understand the optimal triage paradigm, the RACECAT study aimed to examine the clinical outcome in acute ischemic strokes with clinically suspected LVO in the pre-hospital setting who were directly transferred to the EVT-SC versus those transferred to the closest PSC. It was a multicenter, superiority, cluster randomized within a cohort trial with a blinded endpoint assessment. ² Prehospital Rapid Arterial oCclusion Evaluation (RACE) scale was utilized as a triage tool given its strong correlation with clinical neurological exam and its accuracy in assessing stroke severity. ³

Eligible patients were 18 years old or older with a good functional baseline (modified Rankin Scale (mRS) of 0-1) with acute stroke symptoms in the absence of additional an immediate life-threatening condition requiring emergent medical intervention, suspected to have LVO based on a RACE scale of >4, located in geographical areas not covered by the EVT-SC with an estimated arrival to an EVT-SC of less than 7 h from time last known well.  Cluster randomization was performed according to a predefined blinded randomized sequence (temporal cluster design) stratified by territory (metropolitan vs. provincial area) and weekday (working vs. weekend day).  Primary efficacy endpoint is the modified Rankin Scale score at 90 days. The primary safety outcome is mortality at 90 days.

The trial was conducted in the Catalonia region of Spain. Twenty-seven hospitals participated, including 7 EVT-SC and 20 PSC. A total of 1401 patients were randomized. After excluding patients with intracranial and stroke mimic, 949 ischemic stroke patients qualified for modified intention to treat efficacy analysis (PSC, n=467 and EVT-SC, n=482). Of those, 636 subjects (67%) were confirmed to have an LVO. Baseline characteristics between the groups were comparable with an average National Institutes of Health Stroke Scale (NIHSS) score of 17 for both groups. In the PSC cohort, symptom onset to hospital arrival was 142 minutes compared to 216 minutes in EVT-SC group. There were statistically significant differences between the 2 groups regarding IV-tPA and EVT.  More patients in PSC group received IV-tPA, 282 (60.4%) compared to 22 (47.5%) in EVT-SC (p-value <0.001). On the other hand, the EVT-SC group had more patients who underwent EVT 235 (50.0%) compared to 184 (40.9%) in the PSC group (p-value <0.003). Other statistically significant differences between the 2 groups were mostly related to crucial time metrics as follows: Median time from symptom onset to IV-tPA was 120 and 155 minutes in the PSC and EVT-SC, respectively; median time from symptom onset to groin puncture was 270 and 214 minutes in the PSC and EVT-SC, respectively; and the median time from door to groin puncture was 43.0 and 70.5 minutes in the PSC and EVT-SC, respectively.

The primary efficacy endpoint was comparable for both groups with an adjusted hazard ratio (aHR) of 1.02 in EVT-SC vs PSC.  Good outcome (90-day mRS=0-2) was observed in 32.8% in PSC vs 33.4% in EVT-SC cohorts, while mortality (90-day mRS=6) was noted in 37.3% vs 35.8 %, respectively. The 90-day mRS shift analysis was also neutral, with an aHR of 0.965. When considering only patients with hemorrhagic stroke, the aHR for the mRS shift analysis at 90 days was 1.216, which was still insignificant (95% CI, 0.864 – 1.709). This included an increase in mortality among the EVT-SC cohort (48.6%) compared to PSC (40.7%).

This trial addressed the critical issue of optimal pre-hospital triage. It indicated a non-superiority or -inferiority of the concept that all LVO-suspected patients should be redirected to EVT-SC and bypass the nearby PSC. However, it is noteworthy to highlight the well-organized stroke transfer system where the trial was executed which could be challenging to replicate in certain geographical areas. This is clearly reflected by the exceptional “door in and door out” times at the local centers as well as the comparable times of symptoms onset to needle and groin puncture between the 2 groups. Further subgroup analysis looking specifically into transfer times may provide further insights. Finally, despite being non-statistically significant, the trend towards higher mortality in the ICH patients within the EVT-SC group signifies that certain subset of acute stroke patients would benefit from early triage at the PSC (e.g., faster blood pressure control; rapid reversal of coagulopathic state). Stroke severity scales remain imperfect in differentiating ischemic and hemorrhagic strokes and adjunctive modalities (TCDs, MSUs) may be necessary to further discriminate these populations.  At present, the results of the RACECAT trial would suggest that patients continue to be triaged directly to the closest PSC however the results of BEST-MSU and TRIAGE will further inform guidance on getting the right patient to the right hospital.

Courtesy: Transfer to the Local Stroke Center versus Direct Transfer to Endovascular Center of Acute Stroke Patients with Suspected Large Vessel Occlusion in the Catalan Territory (RACECAT). Ribo et al. SVIN 2020 Annual Virtual Conference.

References:

1. Schlemm L, Endres M, Nolte CH. Bypassing the closest stroke center for thrombectomy candidates: What additional delay to thrombolysis is acceptable? Stroke. 2020;51:867-875
2. Abilleira S, Perez de la Ossa N, Jimenez X, Cardona P, Cocho D, Purroy F, et al. Transfer to the local stroke center versus direct transfer to endovascular center of acute stroke patients with suspected large vessel occlusion in the catalan territory (racecat): Study protocol of a cluster randomized within a cohort trial. Int J Stroke. 2019;14:734-744
3. Perez de la Ossa N, Carrera D, Gorchs M, Querol M, Millan M, Gomis M, et al. Design and validation of a prehospital stroke scale to predict large arterial occlusion: The rapid arterial occlusion evaluation scale. Stroke. 2014;45:87-91