The preliminary results of the RACECAT trial—a study comparing transfer of acute stroke patients with suspected large vessel occlusion (LVO) to the closest local stroke centre versus direct transfer to an endovascular stroke centre in the Catalan Territory—were presented at the Stroke Live Course (SLICE; 1–3 October, Nice, France). The data were presented by Marc Ribo, University Hospital Vall d’Hebron, Barcelona, Spain.
Currently, there are 715 patients enrolled in the trial. By the time 701 patients have reached three months of enrolment, safety and efficacy interim analyses will take place—which Ribo predicted will be by the end of 2018.
The authors have collected population and demographic details of the patients, and know for each geographical area of Catalonia how many patients are included, screening failures, as well as how many should have been included but were not; therefore, to quote Ribo, they have a “tight control over what is going on”.
Ribo noted that the interim analysis will determine the future of the trial; explaining that if no significant difference between groups is observed, the probability of stopping the trial is 64%.
It was the approval of endovascular treatment for acute stroke that led Ribo and colleagues to conduct the RACECAT trial. Ribo noted that when a patient is suspected to suffer an acute stroke in the pre-hospital setting, there are no solid data to recommend transfer to the closest primary stroke centre (PSC) or to by-pass the PSC in order to reach a comprehensive stroke centre (CSC). While the first option will prioritise IV t-PA, the latter option will delay IV t-PA in order to advance eventual endovascular treatment. The RACECAT trial aims to generate evidence to answer this important question. If the results suggest that the patient’s outcome would be better if they lived closer to a stroke centre, Ribo claimed that new stroke centres may have to be built to accommodate this.
Secondary endpoints that are being examined include the safety and efficacy of the treatments—in terms of distance travelled and time from onset, in both ischaemic and haemorrhagic stroke. Further, the percentage of patients receiving IV t-PA or endovascular treatment is being analysed.
Ribo noted that the investigators used the pre-hospital RACE scale (rapid arterial occlusion evaluation), in order for the paramedics to assess the stroke patients before they were admitted to hospital. Subsequent improvement or worsening of symptoms can be detected using this parameter; while allowing for a clear distribution of scores. For example, if a patient’s score is 4, there is a 35% probability of large vessel occlusion—yet also a 60% probability of having an ischaemic stroke (requiring t-PA). Therefore, if paramedics were to address the scale and prioritise endovascular treatment; “it may help 35% of the patients,” Ribo said, “but there is still 30–35% of the patients in which we are delaying an effective treatment.”
Addressing the SLICE delegates, Ribo added: “I heard that you are all convinced that we should prioritise transfers to an endovascular capable centre; but you should remember that at the pre-hospital level, there is no good way to know that we have a large vessel occlusion.”
Ribo noted that if only patients with a RACE score higher than 4 are selected, then 30% of this patient population will undergo endovascular treatment. However, if better selection through a quick NIHSS (National Institutes of Health Stroke Scale) score on admission occurred, alongside verifying the Rankin score and performing a Dyna-CT—then 60% of the patients will end up benefitting from endovascular treatment.
Interim data for the RACECAT study was collected from the administrative and safety analysis—inclusive of 400 matched patients, with each group exhibiting a median NIHSS score of 17 at the first hospital admission. Interestingly, the results displayed a discrepancy between what was expected and what was found regarding the RACE scale score distribution, as the investigators were including more severe scales than expected.
The distribution of diagnoses at hospital arrival included patients with a RACE score higher than 4. Ribo stated that the authors expected to see 43% of patients with a large vessel occlusion, while the actual figure that was found was 40.5%.
Ribo et al had estimated an overall endovascular treatment rate of 23.5%; group A (prioritising IV t-PA) was expected to have a 12% rate of endovascular treatment, and group B (prioritising endovascular treatment) was expected to have a rate of 35%. Ribo stated: “Although I do not have data about the findings [as] it is blinded; we think that this is a reasonable difference in terms of access to endovascular treatments […] when keeping in mind that we are talking about patients that are being transferred sometimes more than two hours to the comprehensive stroke centre.”
If only RACE scores of 9 were taken into consideration, Ribo said, around 60% of patients would have a large vessel occlusion. However, the authors also included patients with a RACE score of 5; a score presenting with a 31.5% rate of large vessel occlusion.
Through completion of the RACECAT study, important questions will be answered: where should these patients be primarily transferred, what is the safety of long pre-hospital transfers, and in which geographical areas should be considered for creating a new CSC.