Jose Gutierrez, MD, MPH
Is perfusion imaging useful to predict stroke outcome at 90 days? As per Zhu et al. it might be. The investigators present data on 165 patients with acute stroke secondary to an ICA or m1 occlusion that underwent reperfusion therapy on an average of almost 9 hours from stroke onset, mostly in the form of IA TPA, although a minority received TPA as well. The author obtained, among other clinical variables, the core infarct and perfusion volumes as well as 90 day mRs as the outcome. In ordinal logistic regression, they found that the infract volume can be predicted by clinical and radiological data including CTA but not the perfusion volumes. Recanalization status (yes vs. no), age and baseline NIHSS were all independent predictors of outcome at 90 days. They also found that the perfusion volume was a predictor of good outcome, although it was recanalization status dependent.
The authors in their discussion suggest that learning perfusion status might help identify patients in whom interventions can be planned to rescue the “tissue at risk”. After the International Stroke Conferencepresentations in Honolulu and simultaneous publications of three large acute stroke trials, one of them focused on selecting patients for acute intervention based on “penumbra imaging”, we could say that penumbra imaging per se failed to identify those who might benefit from an intervention (i.e., embolectomy) other than IV TPA. So, how do we contextualize the results by Zhu et al. in the post MR-RESCUE era? Could it be the case that IA TPA and not embolectomy might be beneficial for patients with a penumbra pattern? In IMS-III and MR-Rescue, the time to intervention was significantly shorter than the one presented by Zhu et al., but the rates of good outcome were smaller. What factor can contribute to this observed discrepancy? Are biases from observational studies playing a role? The evolving field of acute stroke treatment has become even more exciting, but “time is brain” and “IV-TPA” appeared to be the only two unscarred concepts to lead the fight.