Endovascular Approaches to Acute Stroke, Part 2: A Comprehensive Review of Studies and Trials

Abstract

SUMMARY:Reperfusion remains the mainstay of acute ischemic stroke treatment. Endovascular therapy has become a promising alternative for patients who are ineligible for or have failed intravenous (IV) thrombolysis. The conviction that recanalization of properly selected patients is essential for the achievement of good clinical outcomes has led to the rapid and widespread growth in the adoption of endovascular stroke therapies. However, comparisons of the recent reperfusion studies have brought into question the strength of the association between revascularization and improved clinical outcome. Despite higher rates of recanalization, the mechanical thrombectomy studies have demonstrated substantially lower rates of good outcomes compared with IV and/or intra-arterial thrombolytic trials. However, such analyses disregard important differences in clot location and burden, baseline stroke severity, time from stroke onset to treatment, and patient selection in these studies. Many clinical trials are testing novel devices and drugs as well as the paradigm of physiology-based stroke imaging as a treatment-selection tool. The objective of this article is to provide a comprehensive review of the relevant past, current, and upcoming data on endovascular stroke therapy with a special focus on the prospective studies and randomized clinical trials. Mirroring its intravenous (IV) counterpart, much of the early work in endovascular stroke therapy has been reported in nonrandomized case series. Reports of successful intra-arterial thrombolysis (IAT) date back to the late 1950s, when Sussmann and Fitch 1 described the recanalization of an acutely occluded internal carotid artery (ICA) with intra-arterial (IA) injection of plasmin. Although pioneering work continued, it was not until the early 1990s that IAT was studied in a more systematic manner. In 2002, Lisboa et al 2 published a meta-analysis regarding the safety and efficacy of this approach. They performed a meta-analysis of 27 studies (minimum of 10 patients in each) with a total of 852 patients who had received IAT and 100 control subjects, in the era before the mechanical thrombectomy trials.3-5 There were more favorable outcomes in the IAT group than in the control group (41.5% versus 23%, P ϭ .002), with a lower mortality rate for IAT (27.2% versus 40%, P ϭ .004). The IAT group had an odds ratio (OR) of 2.4 (95% confidence interval [CI,], 1.45-3.85) for favorable outcome, despite a higher frequency of symptomatic intracranial hemorrhage (SICH; 9.5% versus 3%, P ϭ .046). In addition, they found a trend toward better outcomes with combined IV recombinant tissue plasminogen activator (rtPA) and IAT than with IAT alone. They also remarked that IAT-treated supratentorial strokes were more likely to have favorable outcomes than infratentorial ones (42.2% versus 25.6%, P ϭ .001; OR, 2.0; 95% CI, 1.33-3.0).A recent retrospective study compared 144 patients treated with IAT by using urokinase (UK) within 6 hours of symptom onset versus 147 patients treated with aspirin (250...

Endovascular Stroke Treatment Today

“…First single-center experiences as well as preliminary data from the first postmarket multicenter study seemed to confirm these findings. [39][40][41] In a retrospective case review study in 139 patients treated by the Penumbra System at 7 centers in the United States and Europe, the device was found to successfully recanalize the target vessel in 84% of cases, with similar outcome and intracranial hemorrhage rates as those in the pivotal trial. In fact, 40% of the patients had achieved an mRS score of Ͻ2 at 90 days, which is a significantly higher rate than that reported earlier.…”

The Impact of Thromboemboli Histology on the Performance of a Mechanical Thrombectomy Device

“…[1][2][3][4][5][6][7] However, frequently 2 angiographically identical occluded vessels in patients with acute stroke will respond differently to MT for reasons that are not angiographically evident. One hypothesis is that the performance of the MT device is influenced by the histologic characteristics of thromboembolus (eg, fibrin/cellular component), but current image technology cannot differentiate thromboemboli of varying histologic characteristics.…”

Current and future recanalization strategies for acute ischemic stroke

“…Recanalization refers to restoration of flow through arterial occlusive lesions (AOL) whilst reperfusion means restoration of flow to tissues supplied by the occluded vessel often described by the Thrombolysis in Myocardial Infarction (TIMI) flow grades [36,37]. In the IMS I trial, there was only a modest correlation between the two scores whilst only 49-54% of patients with good-to-excellent recanalization (AOL II ⁄ III) or reperfusion (TIMI II ⁄ III) achieved good clinical outcomes [36].…”