ABC | Volume 114, Nº4, April 2020

Original Article Scherr et al. Interleukin-18 and thrombus precursor protein in CAD Arq Bras Cardiol. 2020; 114(4):692-698 was observed that TpP levels were significantly higher in patients diagnosed with ACS than in patients with chronic CAD and in the control group (p <0.001). However, as this is an observational study, there was no prognostic evaluation of these patients, preventing a better analysis of the clinical outcomes that could be correlated; however, the evaluation of these data is planned. Laurino et al. 21 studied a cohort of 115 patients with symptoms suggestive of AMI with less than six hours duration of pain onset. Blood samples from patients were measured at 0, 1, 2, 4, 8, 16 and 24 hours after presentation for some biomarkers: total creatine kinase (total CK), CK-MB, myoglobin, troponin I and TpP. The authors observed a significant increase in serum TpP levels in 15 of the 17 patients with AMI diagnosed within six hours after symptom onset (p <0.001); 2 of the 8 patients who had AMI diagnosed six hours after symptom onset (p <0.008); 22 of the 35 patients with unstable angina (p <0.001) and 15 of the 30 patients with stable angina (p <0.001) and 3 of the 5 patients with atrial fibrillation (p <0.001); 6 of 9 patients with congestive heart failure (p <0.001); and 6 of 11 patients with non-cardiac chest pain (p <0.001). Maximum TpP concentrations in patients with AMI preceded those of the other markers by two to four hours. 21 Therefore, acute thrombosis is associated with significant clinical alterations, including AMI. An accurate, fast and reliable test for the detection of thrombus would be an invaluable tool for doctors in the diagnosis, monitoring and treatment of patients with acute chest pain. 22 Studies have demonstrated the importance of TpP in the assessment of the acute thrombotic process, highlighting the ACS, while others associate the increased values of this biomarker to the presence of some risk factors for CAD, such as SAH and DM in patients without evidence of ACS. As these risk factors favor a state of hypercoagulability, they may be related to a pro-thrombotic effect and may trigger an active thrombogenic process. The presence of type 2 DM may be associated with increased serum TpP values due to the predisposition of this patient profile to have markedly increased endothelial dysfunction, in addition to greater systemic coagulation activation, which caused transient alterations and favors acute cardiac events. 22,23,24 The presence of SAH can also result in a hypercoagulable and prothrombotic environment and favor acute decompensation of coronary artery disease. 23,24 The present study showed that DM and SAH did not result in a statistically significant difference between the studied groups, having not influenced the final result of the TpP measurement in relation to the different stages of coronary disease (presence of risk factor, chronic CAD and ACS). Therefore, the result obtained was not influenced by these risk factors. Study limitations The sample size is small, representing a convenience sample, which can be attributed to two factors: the selection of patients carried out in hospitals that did not have an open emergency unit, making it difficult to constitute the group of acute patients. The analysis of the means found for IL-18 and TpP showed an equality between the group of chronic patients and the control group. Making a critical assessment of this observation, it can be noted that no complementary exams (e.g., carotid and vertebral Doppler) or intravascular ultrasound were performed to rule out an atherosclerotic process in other sites, which may have influenced this result, not allowing a better evaluation of biomarkers with chronicity or absence of atherosclerosis. A normal ejection fraction in all groups excluded more severe patients, which may have influenced the results. Although the present study showed that the mean serum levels of IL-18 and TpT were higher in the group of acute patients when compared to the group with stable angina or the one without coronary lesions, it is not possible to make a prognostic evaluation, as it aims to encourage the continuity of the research to confirm the hypothesis and intends to do an annual monitoring of the subjects in this sample. Conclusions The mean IL-18 and TpP levels are elevated in the acute phase of coronary artery disease, suggesting the correlation of this biomarker with the worsening and the instability of acute coronary syndrome. The mean levels of IL18 and TpP were lower in the chronic phase of coronary disease and in the patients of the Control Group; however, in this study it was observed that the Chronic Group and the Control Group had statistically equivalent means. The results were not influenced by differences in gender or ethnicity in the groups. Author contributions Conception and design of the research and Critical revision of the manuscript for intellectual content: Scherr C, Albuquerque DC; Acquisition of data: Scherr C, Ataide K, Ludmila T, Blanco F, Mangia CM; Analysis and interpretation of the data and Writing of the manuscript: Scherr C, Albuquerque DC, Ataide K; Statistical analysis: Scherr C, Albuquerque DC, Pozzan R; Obtaining financing: Scherr C, Albuquerque DC, Ludmila T. Potential Conflict of Interest No potential conflict of interest relevant to this article was reported. Sources of Funding This study was funded by Fundação Pró Coração. Study Association This article is part of the thesis of Doctoral submitted by Carlos Scherr, from Universidade do Estado do Rio de Janeiro. 697