Aristeidis H. Katsanos, MD, PhD
This elegant cohort study from the Bernese Stroke registry provides invaluable data on the prevalence rates and reperfusion quality of acute ischemic stroke patients with large vessel occlusion (LVO) after intravenous tissue-type plasminogen activator (tPA) administration and before endovascular treatment (ET). After analyzing data from a total of 627 LVO patients, the authors found that tPA treatment results in occlusion site changes (defined as any change of the proximal thrombus end between initial imaging and the first angiographic run) in one out of ten LVO patients. Additionally, tPA-induced reperfusion with Thrombolysis in Cerebral Infarction (TICI) scores of ≥2a and ≥2b was found in 6.2% [Number Needed to Treat (NNT): 9] and 2.9% (NNT: 20) of all cases. In multivariable analysis, intravenous tPA was found to be independently related with a 11-fold increase on the likelihood of ≥TICI 2a reperfusion score, while in turn ≥TICI 2a reperfusion score was independently associated with a 2-fold increase on the probability of long-term favorable outcome (modified Rankin Scale ≤2 at three months). Of specific note is that pre-ET reperfusion was found to be associated with more favorable clinical outcomes independently of subsequent ET. However, in proximal occlusions (internal carotid artery or proximal M1) intravenous tPA was found to be associated not only with very low rates of successful recanalization but also with increased likelihood of perfusion worsening.
Results from the present study corroborate available literature evidence, while providing further insight on the long-standing debate between bridging therapy (intravenous tPA followed by ET) and direct ET in LVO patients who are eligible for both intravenous tPA and ET. This study confirms that intravenous tPA not only results in non-negligible rates of reperfusion prior to ET, but also independently facilitates post-ET reperfusion, contributing thus independently in better functional outcomes for LVO patients. However, at the same time, study results suggest that no true amendment in the need for subsequent ET in the vast majority of cases exists due to the non-completeness of tPA-achieved reperfusion, while highlighting the limited benefit of intravenous tPA in patients with proximal occlusions.
The controversial conclusion that despite the low odds of angiographically complete recanalization, intravenous tPA is highly and independently associated with better clinical outcomes, further highlights the unique beneficial effect of intravenous tPA in LVOs, an effect potentially mediated through mechanisms other that only vessel recanalization (e.g., collateral circulation augmentation). This notion underscores that intravenous tPA in LVO should be regarded as an invaluable treatment option, which should be used synergistically and not antagonistically to ET.
