Abstract 9814: Patients with Acute Coronary Syndromes Undergoing Percutaneous Coronary Intervention Have Higher Levels of On-Treatment Platelet Reactivity
Introduction: High on-treatment platelet reactivity (HOPR) in patients taking clopidogrel is associated with adverse events following PCI. The impact of presentation with an acute coronary syndrome (ACS) upon levels of on-treatment platelet reactivity, however, is not well-understood.
Hypothesis: We hypothesized that ACS patients, compared to non-ACS patients, would be more likely to have HOPR as measured by the Vasodilator Stimulated Phosphoprotein Phosphorylation (VASP) assay following PCI.
Methods: Patients received 600 mg of clopidogrel and 325 mg aspirin at the time of PCI and underwent platelet reactivity testing with VASP 6-24 hours following PCI. HOPR was defined as a VASP platelet reactivity index >50%. ACS was defined as ≥2 of the following: 1) symptoms consistent with myocardial ischemia; 2) ST-segment elevation or depression ≥1 mm in ≥2 contiguous leads on EKG; 3) cardiac troponin level above the upper limit of normal. VASP platelet reactivity index and HOPR were compared between groups using the Wilcoxon and Chi-square tests, respectively. Multivariable logistic regression was performed to assess the independent effect of ACS upon HOPR.
Results: Overall, 377 patients were enrolled; 12.9% presented with ACS, although none presented with cardiogenic shock. Patients with ACS were less likely to have a history of CAD (22.4% v. 59.8%) or previous PCI (12.5% v. 46.6%) and more likely to have a history of congestive heart failure (22.4% v. 11.6%) or a left anterior descending lesion (47.8% v. 30.2%; p <0.001 for all comparisons). Median VASP platelet reactivity index was higher in ACS patients (52.6% v. 38.3%, p=0.02), as was incidence of HOPR (55.1% v. 34.6%, p=0.007). Following multivariable adjustment, ACS remained significantly associated with HOPR (OR 2.18, 95% CI 1.15-4.12, p=0.02; Table).
Conclusion: Presentation with ACS is a significant risk factor for HOPR. As such, platelet reactivity testing should focus on such high-risk patients.
- © 2011 by American Heart Association, Inc.