ABC | Volume 112, Nº2, February 2019

Original Article Long Term Cardiovascular Outcome Based on Aspirin and Clopidogrel Responsiveness Status in Young ST‑Elevated Myocardial Infarction Patients Mustafa Umut Somuncu, 1 Ali Riza Demir, 2 Seda Tukenmez Karakurt, 2 Huseyin Karakurt, 2 Turgut Karabag 3 Bulent Ecevit University – Faculty of Medicine -, Department of Cardiology, Zonguldak – Turkey Istanbul Mehmet Akif Ersoy Thoracic and Cardiovascular Surgery Training and Research Hospital, Istanbul – Turkey Istanbul University, Istanbul – Turkey Mailing Address: Mustafa Umut Somuncu • Bulent Ecevit University - Tip Fakultesi Dekanlıgı İbn-i Sina Kampusu 67600, Esenkoy/Kozlu, Zonguldak - Turkey E-mail: usomuncu@gmail.com , umutsomuncu@hotmail.com Manuscript received May 07, 2018, revised manuscript July 05, 2018, accepted July 23, 2018 DOI: 10.5935/abc.20180251 Abstract Background: A subset of patients who take antiplatelet therapy continues to have recurrent cardiovascular events which may be due to antiplatelet resistance. The effect of low response to aspirin or clopidogrel on prognosis was examined in different patient populations. Objective: We aimed to investigate the prevalence of poor response to dual antiplatelet therapy and its relationship with major adverse cardiovascular events (MACE) in young patients with ST-elevation myocardial infarction (STEMI). Methods: In our study, we included 123 patients under the age of 45 with STEMI who underwent primary percutaneous intervention. A screening procedure to determine both aspirin and clopidogrel responsiveness was performed on the fifth day of admission. We followed a 2x2 factorial design and patients were allocated to one of four groups, according to the presence of aspirin and/or clopidogrel resistance. Patients were followed for a three-year period. A p-value less than 0.05 was considered statistically significant. Results: We identified 48% of resistance against one or more antiplatelet in young patients with STEMI. More MACE was observed in patients with poor response to dual platelet therapy or to clopidogrel compared those with adequate response to the dual therapy (OR: 1.875, 1.144‑3.073, p < 0.001; OR: 1.198, 0.957-1.499, p = 0.036, respectively). After adjustment for potential confounders, we found that poor responders to dual therapy had 3.3 times increased odds for three-year MACE than those with adequate response to the dual therapy. Conclusion: Attention should be paid to dual antiplatelet therapy in terms of increased risk for cardiovascular adverse events especially in young patients with STEMI. (Arq Bras Cardiol. 2019; 112(2):138-146) Keywords: Acute Coronary Syndrome; Aspirin/adverse effects; Platelet Aggregation; Young Adult; ST ElevationMyocardial Infarction; Mortality. Introduction Acute coronary syndrome (ACS) is considered to be themost important cause of death throughout the world, especially in western countries, despite technological improvements, new drugs and an increasing level of awareness. 1 It has been found that aspirin therapy inhibits cardiovascular and cerebrovascular disease in approximately one out of every four patients. 2 In patients with coronary artery disease, antiplatelet therapy has been included as a Class 1 recommendation in European guidelines. 3 ischemic events continue to occur in a significant proportion of patients on antiplatelet therapy. This can be related to increased platelet activity resulting from the use of these drugs, which is called antiplatelet resistance. Increasing evidence suggests that antiplatelet resistance occurs in varying rates in patients who are at risk for atherothrombotic complications. Moreover, the effect of biochemically detected antiplatelet resistance on cardiovascular adverse events has been found in different studies. 4-6 In a meta-analysis with 50-plus studies, the association of aspirin and clopidogrel resistance with cardiovascular events was clearly indicated. 7 Despite the use of more potent antiplatelets such as ticagrelor and prasugrel, clopidogrel continues to be used in a significant number of patients, sometimes due to financial constraints, and sometimes because of the risk of bleeding. Aspirin and clopidogrel resistance may lead to serious consequences especially in younger myocardial infarction (MI) patients because of the lifelong use. Low response to aspirin and clopidogrel has been studied separately in different groups of patients and its influencing factors have been investigated several times. However, there is insufficient data about both aspirin and clopidogrel response together. In addition, as far as we see, all studies evaluated the prevalence and prognostic effect of the dual antiplatelet resistance on young MI patients. Thus, in our study, the prevalence of aspirin and 138