Hypertension as a Risk Factor for Aspirin and Clopidogrel Resistance in Patients With Stable Coronary Artery Disease

Background: Platelets play an important role in the pathogenesis of coronary artery disease (CAD). The importance of dual antiplatelet therapy to prevent recurrent ischemic events in patients who have acute coronary syndrome and who will undergo percutaneous coronary intervention (PCI) is well known and widely accepted as a gold standard. However, despite this apparently effective therapy, incidence of adverse ischemic events could not be decreased enough. Resistance to aspirin/clopidogrel is an important risk factor for adverse ischemic clinical events. Up-to-date studies revealed many risk factors for antiplatelet resistance, one of which is hypertension (HT). Currently, there is no sufficient number of studies evaluating the association between HT and antiplatelet resistance, which is the aim of this study. Methods: We enrolled 145 consecutive patients (19 female [13.1%], 126 male [86.9%], mean age 55 ± 10) with stable CAD receiving regular antiplatelet therapy composed of 100 mg/d aspirin and 75 mg/d clopidogrel. All patients had been implanted nondrug-eluting coronary stent and/or stents at least 1 month ago. The HT was diagnosed by 24-hour blood pressure (BP) monitoring. Clopidogrel and aspirin resistance was measured by impedance aggregometry method. Results: We included 49 patients with HT and 96 nonhypertensive patients with stable CAD. Aspirin resistance was detected in 22 (16.4%) of 134 patients who received aspirin. Clopidogrel resistance was detected in 55 (37.9%) of 145 patients who received clopidogrel. Prevalance of aspirin and clopidogrel resistance was significantly higher in the hypertensive group than in the nonhypertensive group (P = .030 and P = .007, respectively). Correlation analysis revealed weak but significantly positive correlation between clopidogrel resistance and serum uric acid levels, mean platelet volume, platelet count, and 24-hour mean systolic BP (r = −.180, P = .030; r = .189, P = .016; r = .226, P = .006; and r = .200, P = .016, respectively). Conclusion: We demonstrated higher incidence of antiplatelet resistance in patients with HT. Upon this finding, which is emerged from an actual group of patients with HT, cardioprotective effect of antiplatelet therapy in patients with HT should be argued.