Luciana Catanese, MD
To date, there are no available prediction models to guide physicians in the accurate selection of ischemic stroke patients that will benefit from acute recanalization therapies. CT perfusion (CTP) parameters such as ischemic core volume, penumbra and mismatch profile have shown promising results but not independent from recanalization rates. Therefore, the authors aimed to determine whether the prediction of functional outcomes in acute ischemic stroke (AIS) patients was more accurate when using prediction models including CTP and recanalization parameters versus those without.
Five different hypothetical prognosis algorithms were designed for this purpose, one based on whether or not patients received tPA, a second one based on ASPECTS score of >=7 versus <7, a third one based on the site of occlusion, a fourth one based on volume of ischemic core and penumbra and a fifth one based on a matrix of predicted recanalization (using the ‘iSTROKEMD’ application) and volume of ischemic core and penumbra at baseline. Comparison of sensitivity, specificity, positive and negative predictive value as well as accuracy was made between such algorithms to predict good clinical outcomes, defined as mRS of 0-2 at 90 days.
Retrospective data from 173 patients taken from a repository published previously who were >=18 years, presented within 4.5 hours from symptom onset, had available CT, CTA and CTP on admission as well as CTA or MRA between 1 and 48 hours and who were considered for tPA but did not undergo endovascular therapy were analyzed. Overall, about half of patients were male (median age ~70), had a median ASPECT score of 7, ~50% M1 occlusions and 71.6 % received tPA (54% recanalization versus 34.6% without). Good outcome inversely correlated with admission NIHSS and was overrepresented in those treated with tPA when adjusting for age and baseline NIHSS, as seen in prior studies. Overall, the algorithm that combined the a-priori calculation of the prediction of recanalization with the volume of baseline PCT ischemic core and penumbra was the most accurate in predicting good outcomes with an accuracy of 77.7%. The following table displays the statistical measures of the performance of the different approaches in predicting functional outcomes.
The combination of predicted recanalization and perfusion parameters may be superior in prognosticating good clinical outcomes when compared to other predictors in isolation. However, considering the evolving nature of both CTP thresholds and softwares in accurately and universally measuring ischemic core and penumbra volumes, the small and non-randomized sample, restrospective analysis and lack of inclusion of patients with and without endovascular recanalization, among others, the interpretation of these results is limited. Successful recanalization and baseline tissue fate seem to influence outcomes in AIS patients that undergo recanalization. Closer to the truth but not quite there yet.
