Comparision of resistance rates in coronary artery patients with antitrombotic treatment

Introduction and Objectives: This study aimed to measure drug resistance and frequency of resistance development using the Multiplate electrode aggregometry (MEA) in patients who were diagnosed with coronary artery disease and used acetylsalicylic acid (ASA), clopidogrel, prasugrel, and ticagrelor at least for 6 months. This study also aimed to investigate the relationship between frequency of resistance development and cardiovascular risk factors, gender, and drug regimens. Methods: A total of 165 patients (>18 years old) diagnosed with coronary artery disease and who used antiplatelet drugs (ASA, clopidogrel, prasugrel, ticagrelor) were included in the study. Of these, 53 patients received only ASA treatment, 53 received ASA+ clopidogrel treatment, 12 received ASA+prasugrel treatment, and 47 received ASA+ticagrelor treatment. The thrombocyte aggregation of the patients was performe dusing a MEA. ASPItest reagent was used when ASA resistance was measured using the MEA. For the patients using ASA, values below 71 AUC [U] were regarded as sensitive while those above 71 AUC [U] were regarded as resistant to ASA. ADPtest reagent was used when clopidogrel, prasugrel, and ticagrelor resistance were measure dusing the MEA. For the patients receiving P2Y12 inhibitor drug treatment, values below 57 AUC [U] were regarded as sensitive while those above 57 AUC [U] were regarded as resistant to these drugs.Results: A total of 114 male (%69.1) and 51 female (%30.9) patients (mean age 60.7 ± 1.1 years) constituted the study population. Patients were examined based on their demographic features, drug regimens, and cardiovascular risk factors. Each of 165 patients of the entire study population used ASA, of which 135 (%81.8) were sensitive and 30 (%18.2) were resistant to ASA treatment. Of the 53 patients receiving only ASA treatment, 10 (%18.9) were resistant to ASA treatment. Of the 53 patients receiving ASA+clopidogrel combined treatment, 22 (%41.5) were resistant to clopidogrel treatment. Of the 12 patients receiving ASA+ prasugrel combined treatment, 2 (%16.7) were resistant to prasugrel treatment. Of the 47 patients receiving ASA+ ticagrelor combined treatment, 4 (%8.5) were resistant to ticagrelor treatment. No statistically significant difference was detected while assessing the relationship between drug resistance under ASA, clopidogrel, prasugrel, ticagrelor treatment and the presence of hypertension, diabetes mellitus, smoking, and demographic features (age, gender) (p>0,05). No significant difference was detected when the relationship between the response of drugs used by patients (ACE-i/ARB, B-blocker, CCB) and that of ASA, prasugrel, ticagrelor treatment was examined (p>0,05). However, a statistically significant difference (P = 0.010) was observed when the drug response of ASA+clopidogrel group was examined with the concurrent use of B-blocker. The use of b-blocker treatment was significantly higher in the clopidogrel sensitive group. Conclusions: Many studies have reported that response to antiplatelet treatment is not similar in each patient. There are patients experiencing thrombotic or embolic vascular events although they received a suitable treatment dosage. Many studies on ASA and clopidogrel resistance are available, but studies on ticagrelor and prasugrel drug unresponsiveness or resistance, which use the same receptor as clopidogrel, are lacking. These drugs have recently made their way in the guidelines as class I indication for treatingacute coronary syndromes. The present study aimed to investigate resistance frequencies of prasugrel and ticagrelor besides those of ASA and clopidogrel resistance. This study detected that the highest frequency of resistance was at patients used clopidogrel (%41.5), resistance against prasugrel and ticagrelor is also possible and the lowest frequency of resistance development is at group used ticagrelor (%8.5). Given these high frequencies, performing routine tests for resistance on the patients receiving antiplatelet treatment is crucial for treatment success. However, studies using larger populations are necessary to precisely reveal the frequencies of resistance.