IJCS | Volume 32, Nº5, September/October 2019

450 Soeiro et al. Clopidogrel in elderly patients Int J Cardiovasc Sci. 2019;32(5):449-456 Original Article Thus, this study was developed with the purpose of assessing whether the administration of a 300 mg or 600 mg loading dose of clopidogrel increases in-hospital bleeding rates in patients over 75 years of age. Methods Study population This is a retrospective, unicentric and observational study. We included 174 (12.9% of total) individuals with ACS aged > 75 years, admitted to the emergency sector between May 2010 and May 2015. The patients were divided into two groups: group I: 75 mg loading dose of clopidogrel (N = 129); group II: 300 to 600 mg loading dose of clopidogrel (N = 45). There were no additional exclusion criteria. All patients who met the criteria established by the latest guidelines of the Brazilian Society of Cardiology and the American Heart Association were considered to have had ACS. 3,4 ACS with no ST segment elevation was defined as the presence of chest pain associated with electrocardiographic alterations or rise/drop of troponin upon admission, or, in the absence of these factors, a clinical picture and risk factors consistent with unstable angina (chest painwhen resting or withminimal effort, severe pain, or with an improving pattern). Major bleeding was defined by the score of BARC 9 types 3 and 5, andminor bleeding by types 1 and 2. Reinfarction was considered in cases of recurrence of chest pain linked to the new troponin elevation. Ischemic cerebrovascular accident (iCVA) was considered when the patient displayed new focal motor neurological deficit confirmed through cranial computerized tomography. All patients underwent coronary angiography within the first 24h after admission. All percutaneous coronary interventions (PCI) were performed with conventional stents. The following datawere obtained: age, sex, presence of diabetesmellitus, systemic arterial hypertension, smoking, dyslipidemia, family history of early coronary disease, heart failure, previous coronary artery disease (acute myocardial infarction, angioplasty or previous surgical myocardial revascularization), hemoglobin, creatinine, troponin peak, left ventricular ejection fraction, systolic blood pressure, medications usedwithin the first 24 hours of admission and the coronary treatment adopted. This study was submitted and approved by the Research Ethics Committee. The written informed consent form was signed by all patients included in the study. Statistical analysis The primary in-hospital outcome was bleeding. The secondary outcome was combined events (cardiogenic shock, reinfarction, death, stroke and bleeding). The descriptive analysis was done usingmeans and standard deviation when parametric tests were used and median and interquartile intervals in non-parametric tests. The comparison between groups wasmade throughQ-square for the categorical variables. For continuous variables, when the Komolgorov-Smirnov normality test showed normal distribution, the variables were calculated using the T-test, considering as significant p < 0.05. When the distribution did not follow the normality standard, we used the Mann-Whitney U test. An additional univariate analysis was conducted through Q-square test, comparing mortality between patients who bled versus those who did not present the outcome and also comparing major bleeding rates between groups I and II. The multivaried analysis was performed through logistic regression only when a significant difference was found between the groups in any of the outcomes assessed, and considering as significant p < 0.05. All baseline characteristics presented by Table 1 were considered as variables in the analysis. All calculations were performed using the SPSS Statistics Base v10.0 software.  Results The mean age was 80.2 years in group I versus 80.5 years in group II (p = 0.728). The baseline characteristics of the population studied are presented by Table 1. In relation to the treatment, the performance of PCI was observed in 16.5% in group I and 62.2% in group II (p < 0.0001). Surgical myocardial revascularization was performed in 9.3% of group I versus 4.4% of group II (p = 0.302). In the univariate andmultivariate analysis, significant differences were observed between groups I and II in relation to bleeding rates (8.5% vs. 20%, OR = 0.173; 95% CI: 0.049 – 0.614, p = 0.007), respectively. The results of the univariate and multivariate analysis, comparing different in-hospital outcomes between the groups, are presented by Table 2.