Ischemic Stroke Tissue-Window in the New Era of Endovascular Treatment.

Abstract

Ischemic stroke is a dynamic process of infarct expansion that varies as a function of time, residual blood flow, and other factors. Time can be measured easily but is an imprecise surrogate marker for brain physiology after stroke onset. After sudden intracranial artery occlusion, progression to brain infarction occurs quickly and on average, reperfusion therapies are not effective after several hours.1–4 However, there is enough variance in the rate of infarct development that experienced stroke physicians can identify individual cases using brain imaging where reperfusion will be useful in later time windows after stroke onset. This imaging selective approach has proven effective in recent randomized controlled trials.5–7 Furthermore, the opposite situation also occurs, where the infarction is completed in a short time after stroke onset and reperfusion is futile despite early presentation to medical attention and rapid treatment. The use of time as a surrogate marker for brain physiology has historical precedent with a similar approach having been used in cardiology and in the trials of intravenous thrombolysis for stroke. Time’s advantage is that it is easily and definitively measureable resulting in relative ease of widespread use for guidelines and performance measurement. Brain imaging has advanced and is the most readily available and valuable biomarker for stroke. …