Association between Antiplatelet Therapy and Changes in Intraplaque Hemorrhage in Patients with Mild to Moderate Symptomatic Carotid Stenosis: A Longitudinal MRI Study

Introduction: Carotid atherosclerotic intraplaque hemorrhage (IPH) predicts stroke. Patients with a history of stroke are treated with antiplatelet agents to prevent secondary cardiovascular events. A positive association between previous antiplatelet use and IPH was reported in a cross-sectional analysis. We investigated the changes in IPH over 2 years in patients who recently started versus those with continued antiplatelet use.

Methods: In the Plaque at Risk (PARISK) study, symptomatic patients with <70% ipsilateral carotid stenosis underwent carotid plaque magnetic resonance imaging (MRI) at the baseline and after 2 years to determine IPH presence and volume. Participants were categorized into new users (starting antiplatelet therapy following the index event) and continued users (previous use of antiplatelet therapy before the index event). The association between previous antiplatelet therapy and the presence of IPH at baseline MRI was investigated using multivariable logistic regression analysis. The IPH volume change over a period of 2 years, defined as the difference in volume between follow-up and baseline, was investigated in each group with a Wilcoxon signed-rank test. The IPH volume change was categorized as progression, regression, or no change. Using multivariable logistic regression, we investigated the association between new antiplatelet use and (1) newly developed ipsilateral or contralateral IPH and (2) IPH volume progression.

Results: A total of 108 patients underwent carotid MRI at the baseline and follow-up. At the baseline, previous antiplatelet therapy was associated with any IPH (OR = 5.6, 95% CI: 1.3-23.1; p = 0.02). Ipsilateral IPH volume did not change significantly during the 2 years in patients who continued receiving antiplatelet agents (86.4 mm3 [18.2-235.9] vs. 59.3 mm3 [11.4-260.3]; p = 0.6) nor in the new antiplatelet users (n = 31) (61.5 mm3 [0.0-166.9] vs. 27.7 mm3 [9.5-106.4]; p = 0.4). Similar results of a nonsignificant change in contralateral IPH volume during those 2 years were observed in both groups (p > 0.05). No significant associations were found between new antiplatelet use and newly developed IPH at 2 years (odds ratio [OR] = 1.0, 95% CI: 0.1-7.4) or the progression of IPH (ipsilateral: OR = 2.4, 95% CI: 0.3-19.1; contralateral: OR = 0.3, 95% CI: 0.01-8.5).

Conclusion: Although the baseline association between IPH and previous antiplatelet therapy was confirmed in this larger cohort, the new onset of antiplatelet therapy after transient ischemic attack/stroke was not associated with the newly developed IPH or progression of IPH volume over the subsequent 2 years.