747 HIGH PLATELET REACTIVITY AFTER DAPT IN PATIENTS WITH ACUTE CORONARY SYNDROME AND ATRIAL FIBRILLATION

Abstract

Abstract Background The incidence of atrial fibrillation (AF) in patients who undergo percutaneous coronary intervention (PCI) is not negligible, especially in the elderly. Both oral anticoagulation (OAC) and dual anti-platelet therapy (DAPT) are recommended by main guidelines, therefore is essential to balance the prevention of ischemic events with the risk of bleeding. Evidences from literature suggest that incidence of anti-platelet therapy resistance is higher in elderly patients. There is a paucity of data about the response to antiplatelet therapy in patients with AF. The purpose of this study is to analyze platelet reactivity during DAPT (aspirin + clopidogrel) in elderly patients hospitalized for acute coronary syndrome (ACS), stratifying them by the presence or absence of AF. Methods We analyzed data of patients admitted to our center for ACS. All patients were ≥ 75 years old and treated with DAPT (Aspirin 100 mg daily and Clopidogrel 75 mg daily). At discharge they were tested with a point-of-care antiplatelet-function test (VerifyNow assay) to assess the platelet response to aspirin in aspirin-reaction units (ARU) and to clopidogrel in P2Y12-reaction units (PRU). Low response to aspirin was defined as ARU ≥550; low response to clopidogrel was defined as PRU ≥208; high response was defined as PRU values ≤ 85. Results Among the 216 patients included in the registry we selected 154 of these [median age 81 (IQR 77-87) years; 45% female] who were submitted to the platelet function tested before discharge. Patients were divided into two groups: AF (43 pts); non-AF (111 pts). The table shows the platelet reactivity values by two groups. Conclusions In this series of elderly patients with ACS, AF was associated with higher residual platelet reactivity with both clopidogrel and aspirin. AF patients were significantly less responsive to clopidogrel than non-AF, while among non-AF patients there were significantly more high responders. No difference was found for aspirin low responders between AF and non-AF group. This evidence could assume clinical significance in the choice of antiplatelet drugs to be combined with chronic anticoagulant therapy for AF.