The conceptual mainstay of interventions for acute ischemic stroke is recanalization. The “clot buster” – tPA. The “clot retriever” – the endovascular stent devices. These are interventions aimed at opening an occluded vessel and restoring flow.
But, as it turns out, recanalization is only part of the story. The other half – and the not fully-appreciated utlimate goal – is reperfusion.
This is a small analysis of 46 patients from a prospective, multicenter database undergoing acute magnetic resonance angiography following acute ischemic stroke. All patients had visible sites of arterial occlusion accompanied by a measurable ischemic penumbra. Furthermore, each of these patients underwent subsequent MRA within 6 hours to evaluate recanalization and reperfusion.
Most of the occlusions were proximal, large intracranial vessels – ICA, M1, M2, and M3. Most patients – 34 – received intravenous tPA, while the remaining 12 were managed conservatively. Recanalization occurred in 29% of patients receiving tPA and 25% of those not. However, reperfusion occurred regardless of recanalization – 46% of those receiving tPA and 33% of those not. Univariate analyses regarding improvement in NIHSS and functional outcomes showed the strongest predictor (and, given the small sample, really the only predictor) was not recanalization – it was reperfusion.
Now, recanalization is certainly the most effective method for achieving reperfusion – hence the increasingly favorable results seen in the endovascular trials as device reliability improved. That said, clearly, some of our thinking regarding patient selection is flawed by a narrow approach focused solely on recanalization. There are many logistical hurdles and additional studies needed to translate some of this knowledge into practice, but it appears it may be quite reasonable to withhold acute recanalization therapy if reperfusion has already been spontnaeously, naturally achieved.
The goal, after all – despite the best efforts of pharmaceutical backers – should not be to expand the shotgun spread of recanalization therapies to the largest possible cohort. Rather, we ought to be focusing on finding additional stratification strategies, with a goal of improving patient selection to those with the greatest magnitude of potential benefit.
“Reperfusion Within 6 Hours Outperforms Recanalization in Predicting Penumbra Salvage, Lesion Growth, Final Infarct, and Clinical Outcome”
http://www.ncbi.nlm.nih.gov/pubmed/25908463