The efficacy and safety of argatroban with clopidogrel versus aspirin with clopidogrel for acute minor ischemic stroke (ACAP): study protocol for a multicenter, randomized controlled trial

The ACAP study is a multicenter, randomized controlled trial protocol designed to evaluate the efficacy and safety of combining argatroban with clopidogrel versus aspirin with clopidogrel for improving 90-day outcomes in patients with acute minor ischemic stroke presenting within 72 hours of onset.

The Gist

Imagine your brain is a bustling city with millions of delivery trucks (blood cells) constantly moving through a complex network of roads (blood vessels) to drop off oxygen and nutrients.

Sometimes, a small rock falls onto one of these roads, causing a minor traffic jam. This is a minor ischemic stroke. While the city isn't completely shut down, the traffic is slow, and there's a risk that the jam could get worse or that a new rock could fall nearby, causing a bigger disaster later.

The Current "Traffic Control" Plan

Right now, when a minor traffic jam happens, doctors usually send out two types of "road crews" to clear the blockage and prevent new rocks from falling. These crews are drugs called Aspirin and Clopidogrel. They work together (a strategy called Dual Antiplatelet Therapy, or DAPT) to stop the trucks from clumping together and forming bigger jams.

However, even with these two crews, sometimes the traffic still gets bad, or the jam gets worse within the first few days.

The New Idea: Adding a "Super-Disperser"

The doctors behind this study (the ACAP trial) have a new idea. They want to test if adding a third, special type of road crew called Argatroban works better than just the standard two.

• Argatroban is like a super-liquid that dissolves the sticky glue holding the traffic jams together. It targets a specific protein (thrombin) that acts like the glue.
• The big question is: Does adding this super-liquid help the city recover faster without causing a flood (bleeding)?

The Experiment: A Race Between Two Strategies

The researchers are setting up a massive, fair race across four different cities in China to see which strategy wins.

1. The Race Track: They are looking at 464 drivers (patients) who have just had a minor traffic jam (stroke) within the last 72 hours.
2. The Teams:
   • Team A (The Standard Crew): Gets the usual mix of Aspirin + Clopidogrel.
   • Team B (The Super Crew): Gets Clopidogrel + the new Argatroban super-liquid (given through an IV drip for the first week) + Aspirin is stopped after the first week to keep things safe.
3. The Goal: They want to see who has the best "city recovery" after 90 days.
   • Winning Condition: The driver is back to normal life with no disability (a score of 0 or 1 on a scale of 0 to 6).
   • Safety Check: They are also watching closely to make sure the "Super-liquid" doesn't cause a flood (bleeding in the brain).

Why Do This Now?

Usually, doctors only use the "Super-liquid" (Argatroban) for very severe jams or specific types of patients. But this study is asking: What if we use it earlier and for smaller jams?

Think of it like this: If you have a small leak in your roof, you might just put a bucket under it (standard treatment). But what if using a special sealant (Argatroban) right away would fix the leak permanently and stop water damage before it starts, even if the leak seems small?

The Catch (Limitations)

• It's a bit messy: Because Argatroban is a liquid that needs to be dripped in slowly and monitored carefully, the doctors and patients know who is getting the special treatment. It's not a "blind" test like giving two identical-looking pills. However, the people checking the results at the end (the judges) won't know who got what, so the scoring stays fair.
• The City: The study is happening in a specific region of China, so the results might need to be tested in other "cities" (populations) around the world to be sure it works everywhere.

The Bottom Line

This study is a big experiment to see if adding a powerful, dissolving drug to the standard treatment for minor strokes helps patients recover faster and prevents future disasters, without causing dangerous bleeding. If it works, it could change how doctors treat millions of people with minor strokes worldwide, turning a "maybe" recovery into a "definitely" better one.

Technical Summary

Based on the provided study protocol, here is a detailed technical summary of the ACAP (Argatroban plus Clopidogrel for Stroke) trial.

1. Problem Statement

• Clinical Context: Acute Minor Ischemic Stroke (AMIS), defined as a National Institutes of Health Stroke Scale (NIHSS) score ≤ 5, accounts for approximately half of all acute ischemic strokes. Despite being "minor," these patients face a significant risk of early neurological deterioration (END) within 48–72 hours and a 90-day recurrent stroke risk of 10–20%.
• Current Limitations: The standard of care is Dual Antiplatelet Therapy (DAPT), typically Aspirin plus Clopidogrel. However, DAPT alone still leaves a residual recurrence rate of 8.8–10.1%.
• The Gap: While Argatroban (a direct thrombin inhibitor) is used in Asia for acute stroke, there is a lack of randomized controlled trial (RCT) evidence regarding the efficacy and safety of combining Argatroban with antiplatelet therapy specifically for AMIS patients presenting within a 72-hour window. Existing studies are limited to observational data or trials involving thrombolysis.

2. Methodology

The ACAP study is an investigator-initiated, multicenter, prospective, randomized, open-label trial with blinded endpoint evaluation (PROBE design).

• Study Design:

  • Type: Phase III Randomized Controlled Trial (RCT).
  • Setting: Four stroke centers in China (Guangdong Medical University Affiliated Hospital, Lianjiang People's Hospital, Maoming People's Hospital, Chengyue Hospital).
  • Population: 464 patients (232 per arm) with AMIS (NIHSS ≤ 5) presenting within 72 hours of the last known well.
  • Exclusions: Cardioembolic stroke (e.g., atrial fibrillation), intracranial hemorrhage, severe organ failure, pregnancy, or prior thrombolysis/thrombectomy.

• Intervention Arms:

  • Treatment Group (Argatroban + Clopidogrel):
    • Clopidogrel: 75 mg orally daily for 90 days.
    • Argatroban: Intravenous infusion. Days 1–2: 60 mg/40mL NS at 2 mL/h. Days 3–7: 10 mg/40mL NS twice daily (or 250mL NS at 20 drops/min).
    • Monitoring: Argatroban infusion is titrated to maintain an activated partial thromboplastin time (APTT) at 1.75 × baseline (±10%).
  • Control Group (Aspirin + Clopidogrel):
    • Days 1–7: 100 mg Aspirin + 75 mg Clopidogrel orally daily.
    • Days 8–90: 75 mg Clopidogrel orally daily.
  • Note: Both groups discontinue the second antiplatelet agent (Aspirin or Argatroban) after Day 7, adhering to a short-course DAPT strategy (7 days) followed by monotherapy, based on bleeding risk considerations.

• Endpoints:

  • Primary Efficacy: Proportion of patients achieving an "excellent outcome" (modified Rankin Scale [mRS] score 0–1) at 90 days.
  • Secondary Efficacy: mRS distribution, functional independence (mRS 0–2), independent ambulation (mRS 0–3), END (NIHSS increase ≥4 within 72h), recurrent vascular events, and quality of life (EQ-5D-5L).
  • Primary Safety: Symptomatic Intracranial Hemorrhage (SICH) within 7 days, adjudicated by an independent Imaging Core Laboratory.
  • Secondary Safety: All-cause mortality, serious adverse events, and BARC types 2, 3, and 5 bleeding.

• Statistical Analysis:

  • Sample Size: Calculated to detect a 9% absolute increase in excellent outcomes (from a baseline of ~82.9% with DAPT to ~91.9% with Argatroban) with 80% power and α=0.05, adjusted for 10% loss to follow-up. Total N=464.
  • Methods: Intention-to-treat (ITT) analysis using modified Poisson regression for binary outcomes and generalized odds ratios (GenOR) for ordinal mRS outcomes. Covariate adjustments will be made for baseline NIHSS, age, ASPECTS, and occlusion site.

3. Key Contributions

• Novel Therapeutic Strategy: This is the first RCT to specifically evaluate the combination of a direct thrombin inhibitor (Argatroban) with an antiplatelet agent (Clopidogrel) versus standard DAPT (Aspirin + Clopidogrel) in the specific population of AMIS patients.
• Extended Time Window: The trial investigates a 72-hour therapeutic window for initiating this combination, challenging the traditional 24-hour window often cited for DAPT initiation, based on emerging data suggesting benefit up to 72 hours.
• Optimized DAPT Duration: The protocol tests a 7-day DAPT duration followed by monotherapy, addressing the balance between preventing early recurrence and minimizing bleeding risks associated with prolonged DAPT (21 days).
• Rigorous Safety Monitoring: Utilization of an independent Imaging Core Laboratory for SICH adjudication and a Data and Safety Monitoring Board (DSMB) ensures high-quality safety data.

4. Results

• Current Status: As of the submission of this protocol (March 2026), the trial is ongoing.
• Recruitment: 464 patients have been randomized.
• Interim Analysis: A scheduled interim review was conducted by the DSMB on January 5, 2025. Based on safety data, efficacy endpoints, and protocol adherence, the DSMB recommended the continuation of the trial.
• Outcome Data: No efficacy or safety results are available yet as the follow-up period for the final patient is targeted for November 2026.

5. Significance

• Clinical Impact: If successful, the ACAP trial could establish a new standard of care for AMIS patients, potentially reducing early neurological deterioration and recurrent stroke rates more effectively than current DAPT guidelines.
• Guideline Evolution: Positive results could support the extension of the therapeutic window for antithrombotic interventions to 72 hours and validate shorter durations of DAPT (7 days) to mitigate bleeding risks.
• Global Relevance: While the study is conducted in China, the findings regarding Argatroban (widely used in Asia) and the optimization of antiplatelet/anticoagulant strategies could influence global stroke management guidelines, particularly for patients ineligible for thrombolysis or thrombectomy.
• Limitations to Address: The study acknowledges limitations including its open-label design (mitigated by blinded endpoints), exclusion of cardioembolic stroke (limiting generalizability to atherosclerotic subtypes), and the requirement for continuous IV infusion which may affect patient convenience.

In summary, the ACAP protocol represents a critical step in refining antithrombotic strategies for minor ischemic strokes, aiming to bridge the gap between the high recurrence risk of AMIS and the bleeding risks of aggressive therapy.