Immunohistological Analysis of Intracoronary Thrombus Aspirate in STEMI Patients: Clinical Implications of Pathological Findings

Immunohistochemical characteristics of coronary thrombi in ST-elevation myocardial infarction

Background and aims

The dynamics and implications of intracoronary thrombus constituency in patients with ST-segment elevation myocardial infarction (STEMI) are not fully understood. We evaluated the expression of CD34, CD61and factor VIII surface markers in thrombi of patients with STEMI and its association with clinical and angiographic characteristics and major adverse cardiovascular events (MACE).

Methods

Patients presenting with STEMI undergoing aspiration thrombectomy during primary percutaneous coronary intervention (pPCI) were included. Morphological, histopathological and immunohistochemical aspects of thrombi were assessed by two pathologists blinded to clinical variables and outcomes.

Results

The mean age of the 245 patients included was 58 ± 12 years old, and 70 % were men. Regarding the thrombi microscopic patterns, 61 % were classified as recent, 20 % as lytic and 19 % as organized. There were higher levels of the CD61 index in patients with a history of heart failure. Smokers presented lower CD61 positive cells and CD61 index, but this association did not remain significant after multivariable analysis. There was an inverse correlation between CD61 positive cells and CD61 index with the time from onset of pain to the first medical contact, but no other significant association amongst clinical characteristics and antigenic expression. There was higher expression of the CD61 antigen in patients with in-hospital MACE, but statistical significance was borderline (p = 0.06).

Conclusions

In this cohort of patients with STEMI, immunohistochemistry of coronary thrombus showed a significantly higher platelet content in patients with previous heart failure and a trend in those with in-hospital MACE. Thrombus' platelet content was inversely related to ischemic time.

Insights into the Role of Neutrophils and Neutrophil Extracellular Traps in Causing Cardiovascular Complications in Patients with COVID-19: A Systematic Review

Background: The coronavirus disease 2019 (COVID-19) pandemic caused by the SARS-CoV-2 virus has resulted in significant mortality and burdening of healthcare resources. While initially noted as a pulmonary pathology, subsequent studies later identified cardiovascular involvement with high mortalities reported in specific cohorts of patients. While cardiovascular comorbidities were identified early on, the exact manifestation and etiopathology of the infection remained elusive. This systematic review aims to investigate the role of inflammatory pathways, highlighting several culprits including neutrophil extracellular traps (NETs) which have since been extensively investigated. Method: A search was conducted using three databases (MEDLINE; MEDLINE In-Process & Other Non-Indexed Citations and EMBASE). Data from randomized controlled trials (RCT), prospective series, meta-analyses, and unmatched observational studies were considered for the processing of the algorithm and treatment of inflammatory response during SARS-CoV-2 infection. Studies without the SARS-CoV-2 Infection period and case reports were excluded. Results: A total of 47 studies were included in this study. The role of the acute inflammatory response in the propagation of the systemic inflammatory sequelae of the disease plays a major part in determining outcomes. Some of the mechanisms of activation of these pathways have been highlighted in previous studies and are highlighted. Conclusion: NETs play a pivotal role in the pathogenesis of the inflammatory response. Despite moving into the endemic phase of the disease in most countries, COVID-19 remains an entity that has not been fully understood with long-term effects remaining uncertain and requiring ongoing monitoring and research.

Leptin and leptin receptor evaluation in atherosclerotic plaques in patients with type 2 diabetes mellitus

Background. Diabetes mellitus (DM) is a significant predictor of atherosclerosis, cardiovascular disease, and cardiovascular mortality. It is known that atherosclerosis occurs earlier in patients with diabetes, reducing the duration of their life. Leptin as well as other inflammatory markers can contribute to the progression of atherosclerosis in patients with DM, participate in the development of a local inflammatory reaction. Aim. Determine the cells immunophenotype of atherosclerotic plaques in patients with diabetes. Materials and methods. We analyzed 24 patients (20 men and 4 women), who underwent aortofemoral bypass, femoral-tibial bypass or carotid endarterectomy. During the operation, a fragment of the arterial wall with an atherosclerotic plaque was obtained for further immunohistochemical studies. Five histologic plaque characteristics (CD68+, -SMA, CD34, leptin and leptin receptor) were compared. Results. No difference in the expression of CD68 (p=0.922), -SMA (p=0.192), CD34 (p=0.858), leptin receptor (p=0.741) and leptin (p=0.610) in atherosclerotic plaques were observed between patients with and without DM. The lack of significant differences between the two groups was possibly due to the small number of observations with DM. In particular, when assessing the expression of selected markers in atherosclerotic plaques, patients with DM showed significantly more leptin receptors than patients without DM (2160.716 and 1205.88 respectively); and also significantly less CD68+ (0.39 and 0.98 respectively) and -SMA+ (6.5 and 13.5 respectively). Conclusion. Based on the expression of CD68, -SMA, CD34, leptin receptor and leptin, no significant differences were observed in atherosclerotic plaque between patients with and without DM. At the same time, despite the limitations of the study (a small number of patients, moderate severity of DM, elderly patients in the DM group), we found a tendency in the increased number of leptin receptors and a decreased number of -SMA+, CD68+ in DM atherosclerotic plaques. Further study needed, taking into account the limitations of this work.

Assessment of Neutrophil Extracellular Traps in Coronary Thrombus of a Case Series of Patients With COVID-19 and Myocardial Infarction

Importance

Severe coronavirus disease 2019 (COVID-19) is characterized by the intense formation of neutrophil extracellular traps (NETs), leading to the occlusion of microvessels, as shown in pulmonary samples. The occurrence of ST-elevated myocardial infarction (STEMI) is a serious cardiac manifestation of COVID-19; the intrinsic mechanism of coronary thrombosis appears to still be unknown.

Objective

To determine the role of NETs in coronary thrombosis in patients with COVID-19.

Design, Setting, and Participants

This was a consecutive series of patients with COVID-19 at an academic tertiary hospital in Madrid, Spain, who underwent primary coronary interventions for STEMI in which coronary aspirates were obtained in the catheterization laboratory using a thrombus aspiration device. Patients with COVID-19 who experienced a STEMI between March 23 and April 11, 2020, from whom coronary thrombus samples were aspirated during primary coronary intervention, were included in the analysis. These patients were compared with a series conducted from July 2015 to December 2015 of patients with STEMI.

Main Outcomes and Measures

The presence and quantity of NETs in coronary aspirates from patients with STEMI and COVID-19. The method for the analysis of NETs in paraffin-embedded coronary thrombi was based on the use of confocal microscopy technology and image analysis for the colocalization of myeloperoxidase-DNA complexes and citrullinated histone H3. Immunohistochemical analysis of thrombi was also performed. Clinical and angiographic variables were prospectively collected.

Results

Five patients with COVID-19 were included (4 men [80%]; mean [SD] age, 62 [14] years); the comparison group included 50 patients (44 males [88%]; mean [SD] age, 58 [12] years). NETs were detected in the samples of all 5 patients with COVID-19, and the median density of NETs was 61% (95% CI, 43%-91%). In the historical series of patients with STEMI, NETs were found in 34 of 50 thrombi (68%), and the median NET density was 19% (95% CI, 13%-22%; P < .001). All thrombi from patients with COVID-19 were composed of fibrin and polymorphonuclear cells. None of them showed fragments of atherosclerotic plaque or iron deposits indicative of previous episodes of plaque rupture.

Conclusions and Relevance

In this small case series of patients with COVID-19 and myocardial infarction, NETs seem to play a major role in the pathogenesis of STEMI in COVID-19 disease. Our findings support the idea that targeting intravascular NETs might be a relevant goal of treatment and a feasible way to prevent coronary thrombosis in patients with severe COVID-19 disease.

Molecular signature of coronary stent thrombosis: oxidative stress and innate immunity cells

The clinical impact of in-stent thrombosis is high because it is associated with high mortality and 20 % of the patients suffer a recurrent event within the two following years. The aim of this study was to characterise the morphologic and proteomic profile of in-stent thrombi (IST) in comparison to thrombi developed on native coronary arteries (CT) to identify a differential molecular signature. The study included 45 patients with ST-elevation-myocardial-infarction (STEMI) treated by primary-percutaneous-intervention and thrombus aspiration: 21 had IST and 24 had CT. Thrombi were characterised by morphologic immunohistochemical analysis and differential proteomic profiling (2-DE+MALDI-TOF/TOF). Bioinformatic analysis revealed differences in proteins related to oxidative-stress and cell death/survival. IST showed a higher content of structural proteins (gelsolin, actin-cytoplasmic-1, tropomyosin, and myosin) together with an imbalance in redox-homeostasis related proteins (increased superoxide-dismutase and decreased peroxiredoxin-2 thrombus content), and a coordinated increase of chaperones (HSP60 and HSC70) and cellular quality control-related proteins (26S–protease-regulatory-subunit-7). These changes were reflected into a significant decrease in HSC70 systemic levels and a significant increase in advanced-oxidation-protein-products (AOPP) indicative of increased oxidative stress-mediated protein damage in IST. Our results reveal an imbalance in redox-related proteins indicative of an exacerbated oxidative-stress that leads to an accumulation of AOPP serum levels in IST. Moreover, the coordinated increase in chaperones and regulatory proteins reflects the activation of intracellular protection mechanisms to maintain protein integrity in IST. The failure to counterbalance the stress situation could trigger cellular apoptosis leading to the destabilization of the thrombus and to a worse prognosis of IST-STEMI-patients.

Supplementary Material to this article is available online at www.thrombosis-online.com.