CHANCE

Published

Wang Y, et al. "Clopidogrel with aspirin in acute minor stroke or transient ischemic attack". The New England Journal of Medicine. 2013. 369(1):11-19.
PubMed • Full text • PDF

Clinical Question

Among patients with acute TIA or minor ischemic stroke, does the early administration of aspirin/clopidogrel reduce rates of subsequent strokes when compared to aspirin monotherapy?

Bottom Line

Among patients with acute TIA or minor ischemic stroke, starting aspirin/clopidogrel within 24h of symptom onset reduces the 90-day stroke incidence without increasing bleeding rates, when compared to aspirin monotherapy.

Major Points

The efficacy of single-agent antiplatelet therapy in patients with recent strokes was established by IST (1997; aspirin) and CAPRIE (1996; clopidogrel). A logical extension was that combination therapy with aspirin/clopidogrel may reduce the rate of subsequent stroke even further. This gave rise to MATCH (2004), which demonstrated that aspirin/clopidogrel reduced stroke rates to a similar degree as Plavix monotherapy and conferred an increased risk of bleeding. MATCH was criticized for including patients who would not likely have benefited from antiplatelet therapy as the majority of patients had lacunar infarcts rather than atherothrombotic events. Moreover, the vast majority of antiplatelet trials in stroke have studied patients with recent stroke (ie, <6 months), not patients in the acute stroke setting. Since a large number of subsequent strokes occur early, CHANCE sought to bring dual antiplatelet therapy into the acute setting.

The 2013 Clopidogrel in High-risk patients with Acute Nondisabling Cerebrovascular Events (CHANCE) trial randomized 5,170 Chinese patients with high-risk TIA or minor ischemic stroke within 24 hours of symptom onset to either combination aspirin/clopidogrel or aspirin alone. In the combination group, aspirin was continued for 21 days; all other therapy was continued for 90 days. At 90 days, combination aspirin/clopidogrel was associated with a 3.5% absolute and a 30% relative reduction in subsequent strokes compared to aspirin monotherapy (8.2% vs. 11.7%; NNT=29) driven predominantly by a reduction in ischemic stroke. There was no between-group difference in bleeding rates, which was the trial's primary safety outcome.

The design of the CHANCE trial represents a sea change towards early antiplatelet therapy in CVA management, recognizing that subsequent ischemic events occur early in the post-CVA period. The early use of combination antiplatelet therapy in CHANCE is one of the most significant differences between it and MATCH and is likely the reason that CHANCE was a positive trial. Despite these promising results, the trial's results lack generalizability to Europe and the US. Chinese patients have a larger proportion of undertreated modifiable stroke risk factors (including diabetes and hypertension), a greater burden of large-vessel cerebrovascular disease, and frequently have polymorphisms in genes regulating clopidogrel metabolism. The NIH-sponsored POINT study was published in 2018 and found a reduction in 90-day stroke with DAPT compared to ASA monotherapy at the cost of increased risk of bleeding among patients with minor stroke or TIA.

Guidelines

2018 AHA/ASA Secondary Stroke Prevention Guidelines

• Administration of aspirin is recommended in patients with AIS within 24 to 48 hours after onset. For those treated with IV alteplase, aspirin administration is generally delayed until 24 hours later but might be considered in the presence of concomitant conditions for which such treatment given in the absence of IV alteplase is known to provide a substantial benefit or withholding such treatment is known to cause substantial risk
• Aspirin is not recommended as a substitute for acute stroke treatment in patients who are otherwise eligible for IV alteplase or mechanical thrombectomy.
• The efficacy of IV tirofiban and eptifibatide is not well established. Further clinical trials are needed.
• The administration of another glycoprotein IIb/IIIa receptor antagonists, including abciximab, in the treatment of AIS is potentially harmful and should not be performed. Further research testing the safety and efficacy of these medications in patients with AIS is required
• In patients presenting with minor stroke, treatment for 21 days with dual antiplatelet therapy (aspirin and clopidogrel) begun within 24 hours can be beneficial for early secondary stroke prevention for a period of up to 90 days from symptom onset
• Ticagrelor is not recommended (over aspirin) in the acute treatment of patients with minor stroke

Design

• Multicenter, randomized, placebo-controlled trial
• N=5,170
  • Aspirin (n=2,586)
  • Aspirin/clopidogrel (n=2,584)
• Setting: 114 centers in China
• Enrollment: 2009-2012
• Follow-up: 90 days
• Analysis: Intention-to-treat
• Primary outcome: Stroke

Population

Inclusion Criteria

• Age ≥40 years
• Either of the following:
  • Minor ischemic stroke (NIHSS score ≤3)
  • High-risk TIA (ABCD² score ≥4)
• Symptom onset ≤24 hours

Exclusion Criteria

• CT/MRI brain with hemorrhage, vascular malformations, tumor, abscess, or another similar non-ischemic brain disease
• Isolated sensory symptoms, visual changes, dizziness or vertigo without evidence of acute infarction
• Pre-event Rankin score >2
• Other need for anticoagulation including AF
• History of intracranial hemorrhage
• Need for long-term antiplatelet therapy
• Anticoagulation therapy in prior 10 days
• GI bleeding or major surgery in prior 3 months
• Likely revascularization surgery in following 3 months
• Planned intervention that would require cessation of study medication
• TIA or minor stroke from surgical intervention
• Life expectancy <3 months
• Females with a child-bearing capacity not on contraception without a negative pregnancy test
• Other investigational drug use

Baseline Characteristics

From the aspirin group.

• Demographics: Age 62 years, female 34.7%
• Baseline health data: SBP 150 mmHg, DBP 90 mmHg, BMI 25
• PMH: HTN 65.1%, DM 21.0%, HLD 10.9%, PE <0.1%, ischemic stroke 20.0%, TIA 3.1%, MI 2.0%, angina 3.4%, HF 1.5%, AF/AFL 1.9%, valvular heart disease 0.4%, ever smoker 42.7%
• Symptom onset <12h: 49.5%
• Qualifying event:
  • TIA 28.2%
  • Minor stroke 71.8%
• Mean ABCD² score (for TIAs only): 4

Interventions

• Randomization to one of two groups:
  • Aspirin group received aspirin 75-300mg on day one followed by 75mg daily plus placebo clopidogrel
  • Aspirin/clopidogrel group received clopidogrel 300mg and aspirin 75-300mg on day one, followed by clopidogrel 75mg daily; aspirin was continued at 75mg daily through day 21 and placebo aspirin was given thereafter
• All patients had a CT and/or MRI performed as part of the routine workup
• Thrombolytics were disallowed

Outcomes

Comparisons are aspirin vs. aspirin/clopidogrel. All outcomes are at 90 days.

Primary Outcome

Stroke

11.7% vs. 8.2% (HR 0.68; 95% CI 0.57-0.81; P<0.001; NNT=29)

Secondary Outcomes

Stroke, MI, CV mortality

11.9% vs. 8.4% (HR 0.69; 95% CI 0.58-0.82; P<0.001)

Ischemic stroke: 11.4% vs. 7.9% (HR 0.67; 95% CI 0.56-0.81; P<0.001)

Hemorrhagic stroke: 0.3% vs. 0.3% (HR 1.01; 95% CI 0.38-2.70; P=0.98)

MI: 0.1% vs. 0.1% (HR 1.44; 95% CI 0.24-8.63; P=0.68)

CV mortality: 0.2% vs. 0.2% (HR 1.16; 95% CI 0.35-3.79; P=0.81)

All-cause mortality

0.4% vs. 0.4% (HR 0.97; 0.40-2.33; P=0.94)

TIA

1.8% vs. 1.5% (HR 0.82; 0.53-1.26; P=0.36)

Subgroup Analysis

There was no interaction for the primary endpoint for age, sex, stroke vs. TIA, ABCD² score, history of stroke or TIA, HTN, DM, BP on presentation, or recent aspirin use.

Adverse Events

Bleeding

1.6% vs. 2.3% (HR 1.41; 95% CI 0.95-2.10; P=0.09)

Mild: 0.7% vs. 1.2% (HR 1.57; 95% CI 0.88-2.79; P=0.12)

Moderate: 0.2% vs. 0.1% (HR 0.73; 95% CI 0.16-3.26; P=0.68)

Severe: 0.2% vs. 0.2% (HR 0.94; 95% CI 0.24-3.79; P=0.94)

Criticisms

• Chinese only patients, a population with a much higher rate of stroke (and more large-vessel strokes) than in the US
• Low treatment of comorbid diseases increasing the risk for stroke in the trial population (eg, HTN, DM)
• Low rate of screened patients included as participants
• Polymorphisms affecting clopidogrel metabolism are more common in Chinese patients
• Unknown benefit after 90 days

Funding

Ministry of Science and Technology of the People's Republic of China.