Does “Time Is Brain” Also Mean “Time Is Clot”?
Time Dependency of Tissue-Type Plasminogen Activator–Induced Recanalization in Acute Ischemic Stroke
See related article, p 2734.
Pooled analyses of major randomized controlled trials of intravenous thrombolysis (IVT) in acute ischemic stroke (AIS)1–3 have established the clinical dictum of “Time is Brain”4 because longer times from stroke symptom onset to the initiation of IVT are associated with a lower likelihood of good clinical outcomes at 3 months. Recanalization could be the main mechanism why this time dependency is seen, and the so-called recanalization hypothesis is supported by evidence from a meta-analysis of clinical studies that documented recanalization.5 However, no prospective study to date has demonstrated that indeed shorter onset-to-treatment times (OTTs) result in shorter time to recanalization of an intracranial occlusion, in turn proving it to be the key link to better long-term functional outcomes. Conversely, could this also mean that longer times to treatment produce less recanalization attributable to clot maturation and progression of ischemic injury to brain tissues? Could “Time is Brain” also mean “Time is Clot”? As time is lost, clot wins.
In several pilot single-center studies of real-time monitoring of tissue-type plasminogen activator (tPA) infusion by transcranial Doppler (TCD), both the elapsed time from symptom onset to recanalization6 and the speed of clot lysis7 with IVT thrombolysis were associated with early clinical recovery from AIS as determined by serial National Institutes of Health Stroke Scale assessments. Nevertheless, the effect of the temporal profile of recanalization on 3-month functional outcome after adjusting for potential prognostic factors remains unknown.
In this issue of Stroke …