Implications of the Presence of Non-obstructive Atherosclerotic Plaques on Platelet and Vascular Reactivity

Cardiovascular Risk Factor, Coronary Angiography of Multiple Detectors, Discrete Coronary Artery Stenosis, Platelet Aggregation, Spontaneous

Platelet, Coronary stenosis, Coronary angiography

Approximately 50% of coronary events occur in previously asymptomatic patients. Thus, the early detection of the individuals at higher risk became an important research target within the current cardiology. The various clinical scores used present a predictive accuracy for ischemic events, evaluated by the ROC curve, which ranges from 0.73 to 0, 79. Therefore, the introduction of new non-invasive techniques for the detection of atherosclerosis aims to allow a more adequate classification of risk. The development of radiological techniques, fundamentally coronary angiotomography of multiple detectors (CAMD) and electron beam computed tomography-EBCT‖, demonstrated that the degree of coronary calcification correlates with endothelial lesion and individual prognosis in the long term. Notably, the calcium score has a weak correlation with the severity of coronary stenosis per se, possibly due to variations in arterial remodeling due to coronary calcification. On the other hand, the CAMD allows the detection of a small magnitude atheromatous disease, not diagnosed clinically, nor by tests provoking ischemia, or even by coronary catheterization. The clinical relevance of the small magnitude atheromatous disease diagnosed by the ACMD and its correlation with plaque vulnerability markers, mainly platelet aggregation, vascular reactivity, and inflammation are still not well determined. This is a case and control study and we will enrolled 90 patients with low and medium risk of cardiovascular event whose cases should present discrete plaques in the CAMD e controls should present none plaque in coronary stenosis Coronary atherosclerotic disease often begins in the transition from childhood to adolescence, progressing slowly and quietly. Its clinical manifestation occurs in the majority of cases from the 4th decade of life. However, it is important to remember that necropsy studies conducted in the 1970s identified the presence of non-obstructive atherosclerotic plaques in the aorta of individuals from the second decade of life. From its first description to the present day, the subject has been deeply studied, providing reliable information on several mechanisms involved in atherogenesis, disease progression and plaque unstabilization, which may occur in a silent manner or lead to a clinical picture of unstable myocardial ischemic syndrome (UMIS). In this period, classic risk factors for coronary artery disease (age, sex, diabetes mellitus, systemic arterial hypertension, hypercholesterolemia and smoking, among others) were described, and risk scores were developed that aid in the individual prediction of the probability of disease manifestation coronary artery disease (CAD). The most widespread of these scores is that developed from the population of Framingham, which was started in the United States of the same name after 1948. Subjects with no evidence of cardiovascular disease were followed prospectively with biannual evaluations. The data obtained allowed the elaboration of an algorithm of prediction of individual risk that is included in the most recent recommendations of evaluation of cardiovascular risk. However, these traditional clinical assessment scores tend to underestimate cardiovascular risk in some populations, especially in women and young individuals. In the global population, the various clinical scores used have a predictive accuracy for ischemic events, as assessed by the ROC (Receiver Operating Characteristic) curve, ranging from 0.73 to 0.79. In this way, the concept of "detection interval" is proposed. Defined by the difference between cases of coronary disease or cardiovascular events detected and the actual total prevalence of atherosclerotic disease in the population, such detection interval opens a new field for the introduction of new non-invasive atherosclerosis investigation techniques. Taking into account that approximately 50% of coronary events occur in previously asymptomatic patients, the early detection of these individuals at greater risk has become an important research target within the current cardiology. More recently, the development of radiologic techniques, fundamentally coronary angiography of multiple detectors (CAMD) and electron beam computed tomography (EBCT), have demonstrated that the degree of coronary calcification correlates with endothelial lesion and individual prognosis in the long term, allowing to refine the clinical classification of a patient's risk for a greater or lesser chance of fatal and non-fatal events. Notably, the calcium score has a weak correlation with the severity of coronary stenosis per se, possibly due to variations in the arterial remodeling due to coronary calcification. On the other hand, calcification of the coronary arteries is known to be associated with lower myocardial blood flow even in the absence of significant stenosis. This means that calcification is not merely a marker of obstructive coronary disease and may predispos

The VerifyNow P2Y12® assay provides established cut-off values that allow discrimination of patients with low responsiveness to antiplatelet therapy, with higher PRU values being associated with adverse clinical outcomes. Based on this concept, it is possible to assess the impact of potential platelet hyperreactivity by analyzing the proportion of patients exceeding a predefined clinically relevant threshold. Data collected in this manner allow non-parametric statistical analysis using the McNemar test. A PRU cut-off value of 208 has been widely used in patients treated with clopidogrel and was therefore selected in the present study as the threshold defining inadequate response to the drug. Assuming a 15% difference between the case and control groups, with a statistical power of 95% and a two-sided alpha level of 0.05, a minimum sample size of 82 patients was calculated. Considering an estimated 10% rate of non-inclusion (e.g., refusal to sign informed consent or exclusion due to high Framingham risk score), the final planned sample size for the study was set at 90 participants.

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