Presentations, Diagnosis, and Treatment of Post-COVID Viral Myocarditis in the Inpatient Setting: A Narrative Review.

While coronavirus disease 2019 (COVID-19) infection rates have declined, and mortality outcomes have improved with vaccines, targeted antiviral therapies, and improved care practices over the course of the pandemic, post-acute sequelae of SARS CoV-2 infection (PASC, also referred to as "long COVID") has emerged as a significant concern, even among individuals who appear to have fully recovered from their initial infection. Acute COVID-19 infection is associated with myocarditis and cardiomyopathies, but the prevalence and presentation of post-infectious myocarditis are unclear. We provide a narrative review of post-COVID myocarditis, including symptoms and signs, physical exam findings, diagnosis, and treatment strategies. Post-COVID myocarditis has a wide range of presentations, from very mild symptoms to severe ones that can include sudden cardiac death. Several studies have noted what appears to be a bimodal distribution of affected patients, with individuals under age 16 (particularly males) most affected, followed by those over age 50. The gold standard of diagnosis for myocarditis is endomyocardial biopsy and cardiac magnetic resonance imaging with a confirmed diagnosis of COVID-19. However, if these are not available, other studies such as electrocardiogram, echocardiography, and inflammatory markers can guide clinicians to diagnose post-COVID myocarditis when appropriate. Treatment is largely supportive and may include oxygen therapy, intravenous hydration, diuretics, steroids, and antivirals. Post-COVID myocarditis is rare but important to recognize as more patients present with this condition in the inpatient setting.

Hydrogel delivery of purinergic enzymes improves cardiac ischemia/reperfusion injury.

RATIONALE: The innate immune response contributes to cardiac injury in myocardial ischemia/reperfusion (MI/R). Neutrophils are an important early part of the innate immune response to MI/R. Adenosine, an endogenous purine, is a known innate immune modulator and inhibitor of neutrophil activation. However, its delivery to the heart is limited by its short half-life (<30 s) and off-target side effects. CD39 and CD73 are anti-inflammatory homeostatic enzymes that can generate adenosine from phosphorylated adenosine substrate such as ATP released from injured tissue. OBJECTIVE: We hypothesize that hydrogel-delivered CD39 and CD73 target the local early innate immune response, reduce neutrophil activation, and preserve cardiac function in MI/R injury. METHODS AND RESULTS: We engineered a poly(ethylene) glycol (PEG) hydrogel loaded with the adenosine-generating enzymes CD39 and CD73. We incubated the hydrogels with neutrophils in vitro and showed a reduction in hydrogen peroxide production using Amplex Red. We demonstrated availability of substrate for the enzymes in the myocardium in MI/R by LC/MS, and tested release kinetics from the hydrogel. On echocardiography, global longitudinal strain (GLS) was preserved in MI/R hearts treated with the loaded hydrogel. Delivery of purinergic enzymes via this synthetic hydrogel resulted in lower innate immune infiltration into the myocardium post-MI/R, decreased markers of macrophage and neutrophil activation (NETosis), and decreased leukocyte-platelet complexes in circulation. CONCLUSIONS: In a rat model of MI/R injury, CD39 and CD73 delivered via a hydrogel preserve cardiac function by modulating the innate immune response.

A Hydrogel Strategy to Augment Tissue Adenosine to Improve Hindlimb Perfusion.

[Figure: see text].