NETs a Possible Therapeutic Target for COVID-19 Thrombosis?:
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Researchers in Madrid may have found a clue to the pathogenesis of ST-segment elevation myocardial infarction (STEMI) in patients with COVID-19; it might also offer a therapeutic target to counter the hypercoagulability seen with COVID-19.

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.

The objective of this study was to determine the role of NETs in coronary thrombosis in patients with COVID-19. 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.

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.

-- 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%.

-- In the historical series of patients with STEMI, NETs were found in 34 of 50 thrombi (68%), and the median NET density was 19%.

-- 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.

Conclusively, 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. These 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.