Distinct Coagulopathy With Myocardial Injury and Pulmonary Embolism in COVID-19.

In this article, we report a case of a 61-year-old male who was diagnosed with SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), presenting with acute respiratory distress syndrome requiring intubation and hemodynamic support, marked D-Dimer and troponin I elevation, worsening ST-elevation myocardial infarction on repeat electrocardiograms, and a negative coronary angiogram ruling out a coronary artery thrombosis or occlusion. With worsening diffuse ST-segment elevation on electrocardiograms and reduced ejection fraction on echocardiography in the setting of systemic inflammation, fulminant myocarditis was highly suspected. Despite optimal medical treatment, the patient's condition deteriorated and was complicated by cardiac arrest that failed resuscitation. Although myocarditis was initially suspected, the autopsy revealed no evidence of myocarditis or pericarditis but did demonstrate multiple microscopic sites of myocardial ischemia together with thrombi in the left atrium and pulmonary vasculature. Additionally, scattered microscopic cardiomyocyte necrosis with pathological diagnosis of small vessel micro-thrombotic occlusions. These findings are potentially exacerbated by inflammation-induced coagulopathy, hypoxia, hypotension, and stress, that is, a multifactorial etiology. Further research and an improved understanding are needed to define the precise pathophysiology of the coagulopathic state causing widespread micro-thrombosis with subsequent myocardial and pulmonary injury.

Fibrinolytic Serine Proteases, Therapeutic Serpins and Inflammation: Fire Dancers and Firestorms.

The making and breaking of clots orchestrated by the thrombotic and thrombolytic serine protease cascades are critical determinants of morbidity and mortality during infection and with vascular or tissue injury. Both the clot forming (thrombotic) and the clot dissolving (thrombolytic or fibrinolytic) cascades are composed of a highly sensitive and complex relationship of sequentially activated serine proteases and their regulatory inhibitors in the circulating blood. The proteases and inhibitors interact continuously throughout all branches of the cardiovascular system in the human body, representing one of the most abundant groups of proteins in the blood. There is an intricate interaction of the coagulation cascades with endothelial cell surface receptors lining the vascular tree, circulating immune cells, platelets and connective tissue encasing the arterial layers. Beyond their role in control of bleeding and clotting, the thrombotic and thrombolytic cascades initiate immune cell responses, representing a front line, "off-the-shelf" system for inducing inflammatory responses. These hemostatic pathways are one of the first response systems after injury with the fibrinolytic cascade being one of the earliest to evolve in primordial immune responses. An equally important contributor and parallel ancient component of these thrombotic and thrombolytic serine protease cascades are the serine protease inhibitors, termed serpins. Serpins are metastable suicide inhibitors with ubiquitous roles in coagulation and fibrinolysis as well as multiple central regulatory pathways throughout the body. Serpins are now known to also modulate the immune response, either via control of thrombotic and thrombolytic cascades or via direct effects on cellular phenotypes, among many other functions. Here we review the co-evolution of the thrombolytic cascade and the immune response in disease and in treatment. We will focus on the relevance of these recent advances in the context of the ongoing COVID-19 pandemic. SARS-CoV-2 is a "respiratory" coronavirus that causes extensive cardiovascular pathogenesis, with microthrombi throughout the vascular tree, resulting in severe and potentially fatal coagulopathies.