Intra-arterial reperfusion strategies in acute ischemic stroke

Untreated large vessel occlusions lead to high rates of mortality and morbidity in ischemic stroke. The 'recanalization hypothesis' posits that timely restoration of flow in the ischemic area leads to improved clinical outcomes by salvaging the underperfused and threatened tissue (penumbra). Intravenous thrombolysis is the first-line treatment for reperfusion but recanalization can be slow and incomplete, particularly for proximal occlusions. Intra-arterial approaches have evolved from the local delivery of pharmacological agents to the employment of mechanical devices. While the first-generation approaches (intra-arterial thrombolytic agents, Merci, Penumbra) showed higher rates of recanalization than intravenous treatment, recently published randomized clinical trials failed to show a benefit of intra-arterial over intravenous treatment alone. A new generation of flow restoration devices (Solitaire, Trevo) has been shown in randomized trials to be far superior to the Merci device with respect to both recanalization rates and speed of recanalization translating into significant differences in clinical outcomes. These promising approaches require level I evidence of clinical efficacy compared with medical treatment in order to become standard of care across large patient populations.