Alberta Stroke Program Early CT Scale Evaluation of Multimodal Computed Tomography in Predicting Clinical Outcomes of StrokePatients Treated With Aspiration Thrombectomy. Stroke. 2013
In a forthcoming paper in Stroke, Psychogios et al. investigate the usefulness of ASPECT score, cerebral blood flow (CBF)-ASPECTS and cerebral blood volume (CBV)-ASPECTS in predicting outcomes in 51 patients with M1 occlusion who underwent clot aspiration with the penumbra device. The authors also used the difference between CBV-CBF ASPECTS (Δ(CBV-CBF)-ASPECTS) as evidence of mismatch or area of penumbra. For example, if both the CBV-ASPECT and the CBF-ASPECT have a similar score, then the difference would be near to zero and would imply most of the tissue is already infarcted. On the contrary, a greater difference between these two scores would imply a small “infarct core” with a larger area of “salvageable tissue”. The majority of the patients achieved recanalization (61%) and less than a third had a favorable outcome (27%, defined as MRS ≤ 2) at 90 days. In multivariate analysis, the proportion of patient with favorable outcome was smaller with older age and greater with increasing Δ(CBV-CBF)-ASPECTS. In those who recanalized, only Δ (CBV-CBF)-ASPECTS predicted good outcome.
Several issues arise from this study. First, when three randomized clinical trial have failed to show a benefit for endovascular intervention as adjunct to IV-TPA with or without imaging selection, how do we incorporate the results of this study? If used as hypothesis generator, how would this differ from MR-RESCUE selection process? Second, the proportion of patients with a good outcome in this study is close to what is the natural history of MCA occlusions (around a third of all MCA strokes [Kaste et al. Stroke] or 22% for large artery disease in the NINDS trial placebo arm using a more selective cutoff of MRS ≤ 1) which argues for the futility of the intervention. Finally, although recanalization rates have been associated with better outcomes and despite the greater recanalization rates obtained with devices in randomized clinical trials, achieving recanalization has not been enough to achieve significance compared to IV-TPA.
Where do go from here? What features should the next trial have that incorporates the lessons learned with this and other studies about who might, if any, benefit from interventions other than IV-TPA?