The new AHA guidelines for the use of endovascular therapy in acute ischemic stroke broadly include any patient within six hours of symptom onset. These criteria are based, mostly, on MR-CLEAN – in spite of the follow-up EXTEND-IA, ESCAPE, and SWIFT-PRIME showing the highest yield patients are clearly those with salvageable tissue. Treatment beyond six hours, however, is still considered reasonable – and this cohort from DEFUSE-2 seems to indicate as such.
Based on 78 patients with target mismatch volume on MRI prior to endovascular therapy, they found: time doesn’t matter, only reperfusion. The reperfusion outcomes for intervention under six hours are, grossly, no different than the outcomes for those greater than six hours. And, this makes sense – salvageable tissue is salvageable:
Frankly, this is probably the paradigm for which we should ultimately be moving for all stroke treatment. Time should not be a limiting factor – and, vice versa, should not be the sole indicating factor. Dead brain simply can’t benefit from revascularization – no matter how quickly it is provided, regardless of time window. The traditional “non-contrast head CT” is no longer adequate to provide optimal stroke care – CT angiography with perfusion calculations, or a rapid MRI protocol, should probably form the basis of modern stroke care moving forward.
“Response to endovascular reperfusion is not time-dependent in patients with salvageable tissue”
http://www.ncbi.nlm.nih.gov/pubmed/26224727