INTRODUCTION

Acute myocardial infarction (AMI) is an important cause of death worldwide. The onset of critical processes for coronary artery stenosis is partial or complete coronary artery occlusion due to rupture of atherosclerotic plaque¹. Biomarkers such as creatine kinase and troponin have been used for the early diagnosis of myocardial damage, and it has been shown that these markers can also be used in the prognosis of patients².

Vascular inflammation plays an important role in the pathophysiology of atherosclerosis and coronary artery disease (CAD) (stable or acute coronary syndrome)³. Pentraxin 3 (PTX3) is a multimeric acute phase protein and is an inflammatory glycoprotein like C-reactive protein (CRP)⁴. CRP is in the short pentraxin group; PTX3 is in the long pentraxin group. Unlike CRP synthesized by hepatocytes, PTX3 can be directly synthesized by a variety of cells, such as cells found in atherosclerotic lesions, vascular endothelial cells, smooth muscle cells, and fibroblasts⁵. It has been shown in previous studies that there is an increase in PTX3 levels in patients with AMI and unstable angina pectoris^6,7.

The Gensini score system is a scoring system developed for the assessment of the severity of CAD⁸. The morphology and anatomy of the coronary arteries and the severity of the stenosis are evaluated in the scoring system⁹. Strong correlations were observed between the risk of cardiovascular disease in the long and short term and the Gensini score¹⁰.

In this study, we aimed to investigate the relationship between consecutively measured the Gensini score of serum PTX3 levels and cardiovascular mortality in long-term follow-up in patients with non-ST elevation myocardial infarction (NSTEMI).

MATERIALS AND METHODS

Study Design

In our retrospectively planned study, 119 patients were included. As a result of regular periodic follow-ups (clinic and polyclinic), a total of 55 cases, 18 of whom were NSTEMI and 37 of whom had stable angina pectoris (SAP) (with evidence of coronary artery ischemia, myocardial perfusion scintigraphy or treadmill exercise test) were included in the study. Percutaneous coronary intervention (PCI) was applied to all patients. Our study consists of patients included in the study between February and August 2010 in a tertiary health center.

NSTEMI was defined as ST segment depression or transient ST segment elevation, T wave inversion and troponin positivity in at least two adjacent leads on electrocardiography in addition to typical chest pain lasting longer than 10 minutes. All NSTEMI patients consisted of patients who were hospitalized within 24 hours of the onset of chest pain.

The SAP group was defined as those with at least one coronary artery lesion requiring PCI in coronary angiography (CAG).

Coronary blood flow after PCI was evaluated with the thrombolysis in myocardial infarction (TIMI) frame number¹¹. Patients with TIMI 3 after the procedure were included in the study.

PTX3 levels were measured 3 times for each patient. They were measured at baseline (before CAG), at 8^th hour (after PCI), and at 24^th hour (time after the first measurement).

Patients with a history of persistent ST segment elevation, newly developing left bundle branch block, malignancy, renal failure (serum creatinine >2.0 mg/dL), acute or chronic inflammatory disease were not included in the study.

Approval was obtained from the Çanakkale Onsekiz Mart University Local Ethics Committee for the study (decision no: 2011-KAEK-27/2021-2100169941, date: 24.11.2021), and our study was carried out in accordance with the Declaration of Helsinki.

Coronary Angiographic Analysis and Interventional Procedure

CAG was performed via the femoral or radial artery using the Judkins technique. Coronary arteries were evaluated from images obtained from at least two different angles. PCI was performed using standard technique. Non-ionic low osmolality contrast material was used during the procedure. Angiographic images were evaluated by two interventional cardiologists who were unaware of the study. Quantitative analyses of angiographic images were completed using an automated system (GE Medical Systems). Stenoses greater than 50% for the left main coronary artery and more than 70% for the other coronary arteries were considered clinically significant. The CAG procedure and treatments of the patients were performed within the framework of the current American College of Cardiology/American Heart Society recommendations in the years of the study¹².

Blood Sample Collection and Laboratory Analyses

Blood samples were taken into ethylenediaminetetraacetic tubes and centrifuged and stored at -70 °C until the day the blood samples were to be studied. PTX3 was measured by enzyme-linked immunosorbent assay using the assay kit of Perseus Proteomics Inc., Tokyo, Japan.

Gensini Score Calculation

Gensini score was calculated by considering the degree of stenosis of the lesion in the coronary artery and segment in which it is located. Scoring was done according to the percentage of the degree of stenosis. One point was given for a 0-25% stenosis, 4 points for a 25-50% stenosis, 8 points for a 75-90% stenosis, 16 points for a 90-99% stenosis, and 32 points for a 100% fully occluded stenosis. The Gensini score was obtained by multiplying the scores given with the coefficients for each segment defined in the literature⁸.

Study Endpoints and Follow-up

Follow-up continued for 10 years. The endpoint of the study was cardiovascular mortality. Cardiovascular mortality was defined as decompensated heart failure, fatal arrhythmias disrupting hemodynamics, and deaths due to AMI or unexplained sudden death.

Statistical Analysis

Statistical data were obtained using the Statistical Package for the Social Sciences (SPSS) 20.0 (SPSS Inc, Chicago, IL, USA) application. The Kolmogorov-Smirnov test was used to evaluate the distribution of continuous variables. Continuous variables obtained as a result of the analysis were expressed as mean±standard deviation; categorical variables were expressed as percentages and numbers. Data that failed the Kolmogorov-Smirnov test of normality were expressed as median and width between quartiles of 25-75%. The t-test and Mann-Whitney tests were used to compare the parameters conforming to normal distribution, respectively. Chi-square analysis was used to compare categorical variables and Spearman correlation analysis was used for correlation analysis. Multivariate Cox regression analysis was performed to identify independent predictors of cardiovascular mortality. Kaplan-Meier analysis was performed for PTX3 values measured at the eighth hour for cardiovascular mortality. 95% confidence intervals (CI) were calculated with standardized beta coefficients. P values below 0.05 were considered statistically significant.

RESULTS

Our study consisted of 55 patients in two groups, NSTMI (11 men, 7 women) and SAP (24 men, 13 women). While the median age of the NSTEMI group was 62 (50-64), the median age of the SAP group was 59 (54-64). Demographic and laboratory data of the patients are shown in Table 1. There were no differences between the groups in terms of medical treatments before admission to the cardiology clinic. When PTX3 levels were examined; while no difference was observed between baseline and 24^th-hour values, PTX3 values measured at the eighth hour were higher in the NSTEMI group compared to the SAP group (p=0.006). When the responsible occlusive lesions were compared between the groups, no statistical difference was observed (p=0.947) (Table 1). After 10 years of follow-up, cardiovascular mortality was observed in 6 patients in the NSTEMI group and 2 patients in the SAP group (p=0.011). The median length of life was 63 (49-76) months in the NSTEMI group and 84 (80-88) months in the SAP group (p=0.009) (Table 1).

In the correlation analysis, a significant correlation was observed between baseline PTX3 levels and Gensini score (r=0.299, p=0.026) (Table 2).

In Cox regression analysis, PTX3 levels measured at the eighth hour were found to be an independent predictor of cardiovascular mortality in the NSTEMI group (Hazard ratio: 1.294, 95% CI: 1.024-1.653, p=0.039) (Table 3).

As a result of receiver operating characteristic analysis, the cut-off for PTX3 values measured at the eighth hour was determined as 10.37 (75% sensitivity and 97% specificity p<0.001). Kaplan-Meier analysis for cardiovascular mortality was performed and is shown in Figure 1.

DISCUSSION

In this study, we investigated the relationship of serum PTX3 levels with Gensini score and cardiovascular mortality in long-term follow-up in NSTEMI patients. As a result of the study; while PTX3 levels measured at the time of admission were found to be associated with the severity of CAD, PTX3 measured at the eighth hour was observed to predict cardiovascular mortality in 10-year follow-ups.

PTX3 is an acute phase protein that is similar in structure and function to CRP and belongs to the same family. PTX3 is associated with cardiovascular diseases and is released at high rates from atherosclerotic lesions^13,14. Previous studies have shown that PTX3 is increased in ACS patients and that PTX3 can be used in the risk classification, especially in NSTEMI patients^15,16.

Identifying high-risk groups in ACS patients and initiating optimal treatment in the early period are important to prevent cardiovascular events. Cardiac troponins and CRP are among the most studied biomarkers in ACS patients^17,18. The most important disadvantage of CRP is its elevation in various conditions such as inflammation, malignancy and vasculitis¹⁹. PTX3 is released more specifically from the cells in atherosclerotic region²⁰. Following AMI; while PTX3 plasma levels peak in approximately seven and a half hours, CRP levels peak within 50 hours²¹. In the light of all this information, PTX3 is a special biomarker in ACS patients, unlike CRP. As a matter of fact; PTX3 which was examined in patients with NSTEMI and unstable angina pectoris in the first six hours after the onset of chest pain was found to be more specific in a study in which it was compared with neutrophil activating peptide 2 and cardiac troponin I²².

As can be understood from the case studies in the literature, it is possible that biomarkers have certain limitations in themselves. In our study, we thought that it would be more beneficial to study blood samples in consecutive time periods, not just once, in order to minimize this. When our study results were evaluated, especially when basal PTX3 levels were evaluated, no difference was observed between the NSTEMI and SAP groups. Although the Gensini score, which we used to evaluate the severity of CAD, was numerically higher in the NSTEMI group than in the SAP group in our study, it was not statistically significant. When the previous literature data is interpreted; although the lesions in the coronary arteries are evaluated anatomically and morphologically with the Gensini score, it is not possible to evaluate the content of the plaque causing the stenosis and the inflammatory activity. Therefore, although a correlation was observed with Gensini score and baseline PTX3 values in our study, it would be more accurate for PTX3 values measured consecutively after PCI to provide information about the structure of plaque in the coronary arteries and in terms of the correlation with long-term results. In our study, the eighth hour PTX3 level in the patients after PCI was found to be statistically and numerically significant in the NSTEMI group. As a matter of fact, it has been shown that the deterioration of the vessel layers after coronary stenting causes an increase in PTX3 levels. We think that a similar mechanism is effective in monitoring PTX3 levels higher than basal PTX3 values in our patients. It is known that neutrophils, monocytes and macrophages cause an increase in PTX3 levels in arterial thrombus in patients with AMI²³. In addition to coronary artery stenting, the higher values that were measured at the eighth hour in the NSTEMI patient group compared to the SAP group may be responsible for the increase in PTX3 levels of increased neutrophil, monocytes and macrophage counts in the coronary arteries in NSTEMI patients. In addition, autopsies performed in patients with ACS have shown that inflammatory activity and extracellular matrix compositions differ phenotypically. Larger necrotic nuclei and higher macrophage activity have been demonstrated, particularly in ruptured plaques²⁴. When all this information is evaluated, it is possible that there will be an increase in PTX3 levels after PCI, although vascular patency is achieved with PCI in unstable plaques in NSTEMI patients.

Information on the long-term prognostic value of PTX3 is limited in the literature. It has been shown that PTX3 values measured at admission in ST-elevation myocardial infarction (STEMI) patients are associated with 2-year all-cause mortality, and another study found that PTX3 values measured at the time of admission in patients with STEMI and NSTEMI were associated with cardiovascular mortality in five-year long-term follow-up^25,26. In our study, it is an important advantage to have 10-year follow-up data, and another important difference is that consecutive PTX3 values were examined. Although PTX3 values measured at the time of admission were associated with Gensini score, PTX3 values measured at the eighth hour in long-term follow-up were found to be an independent predictor of cardiovascular mortality.

In-hospital mortality rates are lower in patients with NSTEMI than in patients with STEMI. However, long-term mortality rates are higher in NSTEMI patients compared to STEMI patients²⁷. Therefore, early risk assessment in NSTEMI patients is important in long-term follow-up. PTX3, measured consecutively, can provide clinicians with important information about both the assessment of CAD severity and long-term cardiovascular mortality in NSTEMI patients.

Study Limitations

The most important limitation of our study is that it was conducted with a limited number of patients. However, it was seen in which time period PTX3 levels measured in NSTEMI patients could be used to predict cardiovascular mortality. In our study, superior imaging devices such as 3-dimensional optical coherence tomography could not be used to evaluate the plaque causing stenosis in the coronary arteries and the severity of CAD. However, the Gensini score was used to evaluate the severity of CAD, as suggested in the literature.

CONCLUSION

PTX3 levels are associated with long-term adverse cardiovascular outcomes in hospitalized and treated patients with a diagnosis of NSTEMI. PTX3 can be used for risk classification in NSTEMI patients.

Ethics

Ethics Committee Approval: The study were approved by the Çanakkale Onsekiz Mart University Local Ethics Committee for the study (decision no: 2011-KAEK-27/2021-2100169941, date: 24.11.2021).

Informed Consent: Retrospective study.

Peer-review: Externally peer-reviewed.

Authorship Contributions

Surgical and Medical Practices - Concept – Design - Data Collection or Processing - Analysis or Interpretation - Literature Search - Writing: U.K., B.K., E.E.

Conflict of Interest: No conflict of interest was declared by the authors.

Financial Disclosure: The authors declared that this study received no financial support.