Background and purpose: Randomized trials demonstrated the benefit of dual antiplatelet therapy in patients with minor ischemic stroke or high-risk transient ischemic attack. We sought to determine whether the presence of carotid stenosis was associated with increased risk of ischemic stroke and whether the addition of clopidogrel to aspirin was associated with more benefit in patients with versus without carotid stenosis.
Methods: This is a post-hoc analysis of the POINT trial (Platelet-Oriented Inhibition in New TIA and Minor Ischemic Stroke) that randomized patients with minor ischemic stroke or high-risk transient ischemic attack within 12 hours from last known normal to receive either clopidogrel plus aspirin or aspirin alone. The primary predictor was the presence of ≥50% stenosis in either cervical internal carotid artery. The primary outcome was ischemic stroke. We built Cox regression models to determine the association between carotid stenosis and ischemic stroke and whether the effect of clopidogrel was modified by ≥50% carotid stenosis.
Results: Among 4881 patients enrolled POINT, 3941 patients met the inclusion criteria. In adjusted models, ≥50% carotid stenosis was associated with ischemic stroke risk (hazard ratio, 2.45 [95% CI, 1.68-3.57], P<0.001). The effect of clopidogrel (versus placebo) on ischemic stroke risk was not significantly different in patients with <50% carotid stenosis (adjusted hazard ratio, 0.68 [95% CI, 0.50-0.93], P=0.014) versus those with ≥50% carotid stenosis (adjusted hazard ratio, 0.88 [95% CI, 0.45-1.72], P=0.703), P value for interaction=0.573.
Conclusions: The presence of carotid stenosis was associated with increased risk of ischemic stroke during follow-up. The effect of added clopidogrel was not significantly different in patients with versus without carotid stenosis. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03354429.
Keywords: aspirin; carotid stenosis; clopidogrel; ischemic stroke; proportional hazards models.