Comparison of Prasugrel and Clopidogrel in Thrombotic Stroke Patients with Risk Factors for Ischemic Stroke Recurrence: An Integrated Analysis of PRASTRO-I, PRASTRO-II, and PRASTRO-III.

INTRODUCTION: Patients with stroke are at a high risk of recurrence, and although they receive antiplatelet therapies such as clopidogrel for secondary prevention of non-cardioembolic stroke, the recurrence rate remains high. Three phase 3 trials (PRASTRO-I/II/III) were conducted to determine the efficacy of prasugrel in preventing recurrent stroke. Here, we performed an integrated analysis of these studies to confirm the generalizability of the PRASTRO-III findings and to supplement the small sample size of the study. METHODS: Patients from PRASTRO-I, PRASTRO-II, and PRASTRO-III with ischemic stroke (large-artery atherosclerosis or small-artery occlusion) and at least one of the following were included: hypertension, dyslipidemia, diabetes mellitus, chronic kidney disease, or ischemic stroke history. The primary efficacy endpoint was the composite incidence of ischemic stroke, myocardial infarction (MI), and death from other vascular causes in the intention-to-treat population. Bleeding events (life-threatening bleeding, major bleeding, and clinically relevant bleeding) were evaluated as the primary safety endpoint. Cumulative incidences and 95% confidence intervals (CIs) were calculated for the study outcomes using the Kaplan-Meier method. Hazard ratios (HRs) and 95% CIs were calculated using the Cox regression model. RESULTS: The data of 2,184, 274, and 230 patients from PRASTRO-I, PRASTRO-II, and PRASTRO-III, respectively, were analyzed (N = 2,688; prasugrel, N = 1,337; clopidogrel, N = 1,351). Stroke at enrollment was classified as large-artery atherosclerosis in 49.3% of patients and small-artery occlusion in 50.7% of patients. The primary efficacy endpoint composite incidence (prasugrel vs. clopidogrel) was 3.4% versus 4.3% (HR: 0.771, 95% CI: 0.522-1.138). The incidence of each component of the primary efficacy endpoint for prasugrel versus clopidogrel was 3.1% (n = 41) versus 4.1% (n = 55) for ischemic stroke, 0.3% (n = 4) versus 0.2% (n = 3) for MI, and no events of death from other vascular causes. For the primary safety endpoint, bleeding events were reported in 6.0% of patients in the prasugrel group versus 5.5% of patients in the clopidogrel group (HR: 1.074, 95% CI: 0.783-1.473). CONCLUSIONS: This integrated analysis supports the findings of PRASTRO-III. Prasugrel is a promising treatment that results in a numerical reduction in the composite incidence of ischemic stroke, MI, and death from other vascular causes in patients with ischemic stroke who are at a high risk of stroke recurrence. No major safety issues were observed for prasugrel.

Efficacy and Safety of Prasugrel vs Clopidogrel in Thrombotic Stroke Patients With Risk Factors for Ischemic Stroke Recurrence: A Double-blind, Phase III Study (PRASTRO-III).

AIM: To examine the efficacy and safety of prasugrel vs clopidogrel in thrombotic stroke patients at risk of ischemic stroke. METHODS: This multicenter, active-controlled, randomized, double-blind, double-dummy, parallel group study enrolled thrombotic stroke patients aged ≥ 50 years at risk of ischemic stroke. Patients received prasugrel (3.75 mg/day) or clopidogrel (75 or 50 mg/day) for 24-48 weeks; other antiplatelet drugs were prohibited. The primary efficacy endpoint was the composite incidence of ischemic stroke, myocardial infarction (MI), and death from other vascular causes from the start to 1 day after treatment completion or discontinuation. Secondary efficacy endpoints included the incidences of ischemic stroke, MI, death from other vascular causes, ischemic stroke and transient ischemic attack, and stroke. Safety endpoints included bleeding events and adverse events (AEs). RESULTS: In the prasugrel (N=118) and clopidogrel (N=112; all received 75 mg) groups, the primary efficacy endpoint composite incidence (95% confidence interval) was 6.8% (3.0%-12.9%) and 7.1% (3.1%-13.6%), respectively. The risk ratio (prasugrel/clopidogrel) was 0.949 (0.369-2.443). Secondary efficacy endpoints followed a similar trend. The combined incidences of life-threatening, major, and clinically relevant bleeding were 5.0% and 3.5% in the prasugrel and clopidogrel groups, respectively. The incidences of all bleeding events and AEs were 19.2% and 24.6% and 76.7% and 82.5% in the prasugrel and clopidogrel groups, respectively. No serious AEs were causally related to prasugrel. CONCLUSIONS: We observed a risk reduction of 5% with prasugrel vs clopidogrel, indicating comparable efficacy. There were no major safety issues for prasugrel.

Early Ultrafast Ultrasound Imaging of Cerebral Perfusion correlates with Ischemic Stroke outcomes and responses to treatment in Mice.

In the field of ischemic cerebral injury, precise characterization of neurovascular hemodynamic is required to select candidates for reperfusion treatments. It is thus admitted that advanced imaging-based approaches would be able to better diagnose and prognose those patients and would contribute to better clinical care. Current imaging modalities like MRI allow a precise diagnostic of cerebral injury but suffer from limited availability and transportability. The recently developed ultrafast ultrasound could be a powerful tool to perform emergency imaging and long term follow-up of cerebral perfusion, which could, in combination with MRI, improve imaging solutions for neuroradiologists. Methods: In this study, in a model of in situ thromboembolic stroke in mice, we compared a control group of non-treated mice (N=10) with a group receiving the gold standard pharmacological stroke therapy (N=9). We combined the established tool of magnetic resonance imaging (7T MRI) with two innovative ultrafast ultrasound methods, ultrafast Doppler and Ultrasound Localization Microscopy, to image the cerebral blood volumes at early and late times after stroke onset and compare with the formation of ischemic lesions.Results: Our study shows that ultrafast ultrasound can be used through the mouse skull to monitor cerebral perfusion during ischemic stroke. In our data, the monitoring of the reperfusion following thrombolytic within the first 2 h post stroke onset matches ischemic lesions measured 24 h. Moreover, similar results can be made with Ultrasound Localization Microscopy which could make it applicable to human patients in the future. Conclusion: We thus provide the proof of concept that in a mouse model of thromboembolic stroke with an intact skull, early ultrafast ultrasound can be indicative of responses to treatment and cerebral tissue fates following stroke. It brings new tools to study ischemic stroke in preclinical models and is the first step prior translation to the clinical settings.