Rationale and design of a randomised double-blind 2×2 factorial trial comparing the effect of a 3-month intensive statin and antiplatelet therapy for patients with acute mild ischaemic stroke or high-risk TIA with intracranial or extracranial atherosclerosis (INSPIRES)

Clopidogrel and Aspirin Initiated Between 24 to 72 Hours for Mild Ischemic Stroke: A Subgroup Analysis of the INSPIRES Randomized Clinical Trial

Importance

Prior trials showed that dual antiplatelet therapy could reduce the risk of early new stroke in patients with acute mild ischemic stroke or transient ischemic attack (TIA) within 24 hours of symptom onset. However, it is currently uncertain whether dual antiplatelet therapy can reduce the risk of early new stroke in patients with a more delayed initiation time window.

Objective

To evaluate the efficacy and safety of clopidogrel and aspirin among patients with mild ischemic stroke or TIA when initiated within 24 hours, from more than 24 hours to 48 hours, and from more than 48 hours to 72 hours.

Design, Setting, and Participants

The Intensive Statin and Antiplatelet Therapy for Acute High-Risk Intracranial or Extracranial Atherosclerosis randomized clinical trial was a double-blind, placebo-controlled, multicenter, 2-by-2 factorial randomized clinical trial conducted at 222 hospitals in China from September 17, 2018, to October 15, 2022. All patients with acute mild ischemic stroke and TIA were included in this subgroup analysis and categorized into 3 groups according to time from symptom onset to randomization (group 1: ≤24 hours; group 2: >24 to ≤48 hours; and group 3: >48 to 72 hours). Patients were followed up for 90 days.

Interventions

All patients received clopidogrel combined with aspirin (clopidogrel 300 mg loading dose on day 1, followed by 75 mg daily on days 2 to 90, and aspirin 100 to 300 mg on the first day and then 100 mg daily for days 2 to 90) or aspirin alone (100 to 300 mg on day 1 and then 100 mg daily for days 2 to 90) within 72 hours after symptom onset.

Main Outcomes and Measures

The primary outcome was new stroke (ischemic or hemorrhagic) within 90 days. The primary safety outcome was moderate-to-severe bleeding, according to Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries criteria.

Results

This analysis included a total of 6100 patients (3050 in the clopidogrel-aspirin group and 3050 in the aspirin group). The median age was 65 years (IQR, 57-71 years), and 3915 patients (64.2%) were male. In the population with time to randomization of 24 hours or less, stroke occurred in the next 90 days in 97 of 783 patients (12.4%); among those randomized from more than 24 hours to 48 hours, in 211 of 2552 patients (8.3%) among those randomized from more than 24 hours to 48 hours, and in 193 of 2765 patients (7.0%). The clopidogrel-aspirin group had a lower risk of new stroke within 90 days compared with the aspirin alone group both in patients with time to randomization of from 48 to 72 hours (5.8% vs 8.2%; hazard ratio [HR], 0.70 [95% CI, 0.53-0.94]), of more than 24 to 48 hours (7.6% vs 8.9%; HR, 0.85 [95% CI, 0.65-1.12]), and of 24 hours or less (11.5% vs 13.4%; HR, 0.83 [95% CI, 0.55-1.25]) (P = .38 for interaction). Among those with time to randomization of more than 48 to 72 hours, moderate-to-severe bleeding occurred in 12 patients (0.9%) in the clopidogrel-aspirin group and in 6 patients (0.4%) in the aspirin-alone group (HR, 2.00 [95% CI, 0.73-5.43]), while moderate-to-severe bleeding in those with time to randomization of more than 24 hours to 48 hours occurred in 9 patients (0.7%) in the clopidogrel-aspirin group and in 4 patients (0.3%) in the aspirin-alone group (HR, 2.25 [95% CI, 0.68-7.39]) and in those with time to randomization of within 24 hours, occurred in 6 patients (1.5%) in the clopidogrel-aspirin group and in 3 patients (0.8%) in the aspirin-alone group (HR, 1.57 [95% CI, 0.36-6.83]) (P = .92 for interaction).

Conclusions and Relevance

In this randomized clinical trial of antiplatelet therapy in China, patients with mild ischemic stroke or TIA had consistent benefit from dual antiplatelet therapy with clopidogrel and aspirin vs aspirin alone when initiated within 72 hours after symptom onset, with a similar increase in the risk of moderate-to-severe bleeding. Patients should receive dual antiplatelet therapy with clopidogrel and aspirin within 72 hours after symptom onset.

Trial Registration

ClinicalTrials.gov Identifier: NCT03635749.

Should patients with minor strokes be given thrombolytics?

Mild stroke symptoms are cited as the reason for not using tissue-type plasminogen activator in 29-43% of time-eligible patients. Previous studies suggested that not all of these patients had a good recovery or even survival to hospital discharge. Since then, stroke guidelines worldwide recommended thrombolysis in minor but disabling strokes.Dual antiplatelet treatment with aspirin and clopidogrel was more effective than aspirin alone for reducing subsequent events in patients with minor stroke if started within 24 hours of onset in both CHANCE (Clopidogrel in High-Risk Patients with Acute Non-disabling Cerebrovascular Events) and POINT (Platelet-Oriented Inhibition in New TIA and Minor Ischaemic Stroke) trials. Recently, both PRISMS (The Potential of rtPA for Ischemic Strokes With Mild Symptoms) trial and TEMPO-2(The Potential of rtPA for Ischemic Strokes With Mild Symptoms) trial showed that treatment with thrombolysis versus antiplatelet did not increase the likelihood of favourable functional outcome at 90 days among patients with minor non-disabling acute ischaemic strokes. Therefore, a narrative review on thrombolysis for patients with minor strokes from published studies may help practicing clinicians.

Immediate- or Delayed-Intensive Statin in Acute Cerebral Ischemia: The INSPIRES Randomized Clinical Trial

Importance

Comparisons are limited for immediate-intensive and delayed-intensive statin for secondary stroke prevention and neuroprotection in patients with acute mild ischemic stroke or transient ischemic attack (TIA) from atherosclerosis.

Objective

To estimate whether immediate-intensive statin therapy is safe and can lower the risk of recurrent stroke compared with delayed-intensive statin in patients with acute mild ischemic stroke or high-risk TIA from atherosclerosis.

Design, Setting, and Participants

The Intensive Statin and Antiplatelet Therapy for High-Risk Intracranial or Extracranial Atherosclerosis (INSPIRES) trial, a double-blind, placebo-controlled, 2 × 2 factorial, randomized clinical trial enrolled patients from September 2018 to October 2022. The trial was conducted at 222 hospitals in China. Patients aged 35 to 80 years with mild ischemic stroke or high-risk TIA of presumed atherosclerosis within 72 hours of symptom onset were assessed.

Interventions

Patients were randomly assigned to receive immediate-intensive atorvastatin (80 mg daily on days 1-21; 40 mg daily on days 22-90) or 3-day delayed treatment (placebo for days 1-3, followed by placebo and atorvastatin, 40 mg daily on days 4-21, and then atorvastatin, 40 mg daily on days 22-90).

Main Outcomes and Measures

The primary efficacy outcome was new stroke within 90 days, and a secondary efficacy outcome was poor functional outcome. Moderate to severe bleeding was the primary safety outcome.

Results

A total of 11 431 patients were assessed for eligibility, and 6100 patients (median [IQR] age, 65 [57-71] years; 3915 men [64.2%]) were enrolled, with 3050 assigned to each treatment group. Within 90 days, new stroke occurred in 245 patients (8.1%) in the immediate-intensive statin group and 256 patients (8.4%) in the delayed group (hazard ratio, 0.95; 95% CI, 0.80-1.13). Poor functional outcome occurred in 299 patients (9.8%) and 348 patients (11.4%) in the immediate-intensive and delayed-intensive statin groups, respectively (odds ratio, 0.83; 95% CI, 0.71-0.98). Moderate to severe bleeding occurred in 23 of 3050 patients (0.8%) and 17 of 3050 patients (0.6%), in the immediate-intensive and delayed-intensive statin groups, respectively.

Conclusions and Relevance

Immediate-intensive statin initiated within 72 hours did not reduce the risk of stroke within 90 days and may be associated with improved functional outcomes without significant difference in moderate to severe bleeding, compared with 3-day delayed-intensive statin in Chinese patients with acute mild ischemic stroke or TIA from atherosclerosis.

Trial Registration

ClinicalTrials.gov Identifier: NCT03635749.

The pharmacology of antiplatelet agents for primary, secondary, and tertiary prevention of ischemic stroke

INTRODUCTION

Ischemic etiology accounts for two thirds of all strokes in which platelet activation and aggregation play a major role. A variety of antiplatelet therapies have been tested for primary, secondary, and tertiary prevention, with certain patient subtypes benefiting more than others from a specific regimen.

AREAS COVERED

This review aims at synthetizing current evidence on pharmacology of antiplatelet agents approved for primary, secondary, and tertiary stroke prevention and their application among possible patient subtypes that may benefit more from their administration.

EXPERT OPINION

Management of ischemic stroke has largely evolved over the past decades. A better understanding of stroke pathophysiology has allowed to identify patients who can benefit most from antiplatelet therapies, with varying degrees of benefit depending on whether these agents are being used for primary, secondary, or tertiary prevention. Importantly, the antiplatelet treatment regimens currently available have expanded and no longer limited to aspirin but include other drugs such as P2Y12 and phosphodiesterase inhibitors, also used in combination, as well as precision medicine approaches using genetic testing aiming at optimizing the safety and efficacy in this population.

Dual Antiplatelet Treatment up to 72 Hours after Ischemic Stroke

BACKGROUND

Dual antiplatelet treatment has been shown to lower the risk of recurrent stroke as compared with aspirin alone when treatment is initiated early (≤24 hours) after an acute mild stroke. The effect of clopidogrel plus aspirin as compared with aspirin alone administered within 72 hours after the onset of acute cerebral ischemia from atherosclerosis has not been well studied.

METHODS

In 222 hospitals in China, we conducted a double-blind, randomized, placebo-controlled, two-by-two factorial trial involving patients with mild ischemic stroke or high-risk transient ischemic attack (TIA) of presumed atherosclerotic cause who had not undergone thrombolysis or thrombectomy. Patients were randomly assigned, in a 1:1 ratio, within 72 hours after symptom onset to receive clopidogrel (300 mg on day 1 and 75 mg daily on days 2 to 90) plus aspirin (100 to 300 mg on day 1 and 100 mg daily on days 2 to 21) or matching clopidogrel placebo plus aspirin (100 to 300 mg on day 1 and 100 mg daily on days 2 to 90). There was no interaction between this component of the factorial trial design and a second part that compared immediate with delayed statin treatment (not reported here). The primary efficacy outcome was new stroke, and the primary safety outcome was moderate-to-severe bleeding - both assessed within 90 days.

RESULTS

A total of 6100 patients were enrolled, with 3050 assigned to each trial group. TIA was the qualifying event for enrollment in 13.1% of the patients. A total of 12.8% of the patients were assigned to a treatment group no more than 24 hours after stroke onset, and 87.2% were assigned after 24 hours and no more than 72 hours after stroke onset. A new stroke occurred in 222 patients (7.3%) in the clopidogrel-aspirin group and in 279 (9.2%) in the aspirin group (hazard ratio, 0.79; 95% confidence interval [CI], 0.66 to 0.94; P = 0.008). Moderate-to-severe bleeding occurred in 27 patients (0.9%) in the clopidogrel-aspirin group and in 13 (0.4%) in the aspirin group (hazard ratio, 2.08; 95% CI, 1.07 to 4.04; P = 0.03).

CONCLUSIONS

Among patients with mild ischemic stroke or high-risk TIA of presumed atherosclerotic cause, combined clopidogrel-aspirin therapy initiated within 72 hours after stroke onset led to a lower risk of new stroke at 90 days than aspirin therapy alone but was associated with a low but higher risk of moderate-to-severe bleeding. (Funded by the National Natural Science Foundation of China and others; INSPIRES ClinicalTrials.gov number, NCT03635749.).

Antithrombotic Therapy for Primary and Secondary Prevention of Ischemic Stroke: JACC State-of-the-Art Review

Stroke is a devastating condition with significant morbidity and mortality worldwide. Antithrombotic therapy plays a crucial role in both primary and secondary prevention of stroke events. Single or dual antiplatelet therapy is generally preferred in cases of large-artery atherosclerosis and small-vessel disease, whereas anticoagulation is recommended in conditions of blood stasis or hypercoagulable states that mostly result in red thrombi. However, the benefit of antithrombotic therapies must be weighed against the increased risk of bleeding, which can pose significant challenges in the pharmacological management of this condition. This review provides a comprehensive summary of the currently available evidence on antithrombotic therapy for ischemic stroke and outlines an updated therapeutic algorithm to support physicians in tailoring the strategy to the individual patient and the underlying mechanism of stroke.