Intra-arterial Therapy for Acute Ischemic Stroke

Abstract

Intra-arterial therapy (IAT) for acute ischemic stroke refers to endovascular catheter-based approaches to achieve recanalization using mechanical clot disruption, locally injected thrombolytic agents or both. IAT may be used in addition to intravenous tissue plasminogen activator (tPA) or in patients who do not qualify for tPA, usually because they are outside the approved 3-h timeframe window or have contraindications, such as elevated international normalized ratio or partial thromboplastin time. Recanalization rates correlate with clinical improvement, and with the newest catheters it is possible to achieve recanalization in roughly 80% of patients treated. However, while the catheters are approved by the Food and Drug Administration, there are still no randomized trial data demonstrating the role of current IAT therapy vs either tPA or standard management. IAT is reserved for patients with large artery occlusions in the basilar, distal carotid, or proximal middle cerebral arteries. Imaging the penumbra using magnetic resonance imaging or computed tomographic perfusion is currently the most frequently used way to identify patients who might benefit. However, the imaging and clinical criteria for identifying which patients benefit, and perhaps more importantly those who will do poorly despite IAT, remain unclear.

Utility of a rescue endovascular therapy for the treatment of major strokes refractory to full-dose intravenous thrombolysis

“…We achieved an overall successful recanalization rate (TICI $2) of approximately two-thirds (68.7%) of patients, which is comparable to other studies. 1 Despite the generally poor prognosis of patients with M-AIS and failed IVT, we found only a general trend towards better functional results after 3 months in the group undergoing additional IAT and no statistically significant differences compared with the IVT treatment alone. A goodmoderate functional result (mRS #3) was observed in approximately one-third of patients (34.4%), which corresponds to the approximately 50% of patients with long-term functional outcomes after successful recanalization as noted by Hallevi et al 3 Some researchers believe that IAT may be beneficial for patients with diminished collateral circulation; typically, in proximal MCA occlusions, approximately a quarter of patients have a poor collateral flow measured by the Sylvian fissure and the leptomeningeal convexity vessels on CT angiography.…”

“…By contrast, patients with the most severe strokes (NIHSS .20) have a high probability of large and more proximal vessel occlusions, which predicts poor revascularization by intravenous thrombolysis (IVT) alone and leads to poorer outcomes regardless of treatment methods. 1 Prompt reperfusion of the ischaemic brain is the cornerstone of effective therapy for AIS and results in better clinical outcomes. IVT is currently the only validated approach for the effective treatment of stroke patients.…”

“…The traditional time window for AIS treatment is prolonged for intra-arterial thrombolysis (IAT) to 6 h and for endovascular mechanical recanalization (EMR) up to 8 h from stroke onset or from the last time the patient was known to be without symptoms. 1,2 Although IAT is the standard treatment in many centres, it remains an off-label therapy for any available fibrinolytic agent that requires further confirmation of its safety and efficacy for on-label applications. The hypothesis of our study is that intraarterial delivery of a fibrinolytic agent directly into the thrombus forms a relatively high local concentration of the agent that cannot be achieved by systemic administration.…”

“…However, patients with a major AIS (M-AIS; NIHSS .20) who have a high probability of LAO and/or large thrombus length respond less well to IVT, thus these specific patients could profit from endovascular techniques. 1 The aim of our study was to compare recanalization rates and outcomes of rescue IAT and EMR in patients with M-AIS who do not improve after full-dose IVT.…”

“…13 However, our results cannot be directly compared with those of studies comprising patients with the full spectrum of stroke severity because the severity of a stroke as expressed by NIHSS at admission is only one important predictor of the outcome. 1 Broderick et al 13 also speculated that the efficacy of endovascular therapy would be greater mainly in participants with severe stroke (NIHSS score $20). Nevertheless, they have found no significant difference in the proportion of patients with a good outcome (mRS #2) after 90 days when comparing their endovascular-therapy group and their group undergoing IVT alone; they achieved only 23.8% good outcomes after endovascular treatment.…”