SARS-CoV-2 Myocarditis: Insights Into Incidence, Prognosis, and Therapeutic Implications

Abstract

Purpose of Review In coronavirus disease 2019 (COVID-19), myocardial injury occurs frequently in severe or critically ill hospitalized patients, yet myocarditis is much less common. In this context, revisiting the definition of myocarditis is appropriate with a specific focus on diagnostic and management considerations in patients infected with SARS-CoV-2. Recent Findings Pathologic cardiac specimens from patients with COVID-19 suggest a mixed inflammatory response involving lymphocytes and macrophages, and importantly, cellular injury occurs predominantly at the level of pericytes and endothelial cells, less often involving direct myocyte necrosis. In COVID-19, the diagnosis of myocarditis has understandably been based predominantly on clinical criteria, and the number of patients with clinically suspected myocarditis who would meet diagnostic histological criteria is unclear. Echocardiography and cardiac magnetic resonance are important diagnostic tools, although the prognostic implications of abnormalities are still being defined. Importantly, SARS-CoV2 myocarditis should be diagnosed within an appropriate clinical context and should not be based on isolated imaging findings. Therapies in COVID-19 have focused on the major clinical manifestation of pneumonia, but the promotion of viral clearance early in the disease could prevent the development of myocarditis, and further study of immunosuppressive therapies once myocarditis has developed are indicated. Summary A strict and uniform approach is needed to diagnose myocarditis due to SARS-CoV-2 to better understand the natural history of this disease and to facilitate evaluation of potential therapeutic interventions. A methodological approach will also better inform the incidence of COVID-19 associated myocarditis and potential long-term health effects.

A 63-year-old man with hypoxemia and shock after initial recovery from COVID-19 pneumonia

“…Around 10%–35% of hospitalized COVID-19 patients have acute cardiac injury defined as an elevated high-sensitivity troponin I or troponin T above the 99 th percentile upper reference range. [ 13 ] Myocarditis and the associated systemic inflammation can be delayed up to a month after initial SARS-CoV-2 infection. [ 14 ] However, pathologic myocarditis is rare.…”

Myocardial Injury Complicated by Systolic Dysfunction in a COVID-19-Positive Dog

“…However, as COVID-19 is a polymorphic disease characterised by great variability in clinical presentation, non-respiratory complications may sometimes occur [ 19 , 20 , 21 ]. In humans, cardiac involvement during SARS-CoV-2 infection has been documented by many authors and represents a source of great concern [ 22 , 23 , 24 ]. The mechanisms that lead to cardiac involvement in the setting of COVID-19 include direct injury caused by direct viral entry to cardiomyocytes, which is possible by direct viral binding to the angiotensin-converting enzyme 2 present on these cells, hypoxia-induced myocardial ischaemia, and exaggerated inflammatory response characterised by endothelial overactivation and microvascular thrombi [ 22 , 23 , 24 ].…”

“…In humans, cardiac involvement during SARS-CoV-2 infection has been documented by many authors and represents a source of great concern [ 22 , 23 , 24 ]. The mechanisms that lead to cardiac involvement in the setting of COVID-19 include direct injury caused by direct viral entry to cardiomyocytes, which is possible by direct viral binding to the angiotensin-converting enzyme 2 present on these cells, hypoxia-induced myocardial ischaemia, and exaggerated inflammatory response characterised by endothelial overactivation and microvascular thrombi [ 22 , 23 , 24 ]. Histologically, this may trigger non-myocarditis inflammatory infiltrates, acute myocardial infarction, and, rarely, myocarditis [ 47 , 48 ], which represent the anatomical prerequisites for the development of clinical complications, such as LV systolic dysfunction, congestive heart failure and arrhythmias [ 22 , 23 , 24 ].…”

“…Given the above, clinical reports are needed, as they would help veterinarians in correctly interpreting findings from pets that have developed overt signs during a COVID-19 wave and/or have tested positive for SARS-CoV-2. In line with this need, this work aimed to report the development of myocardial injury (MI) complicated by left ventricular (LV) systolic dysfunction in a COVID-19-positive dog, a clinical picture poorly documented in this species [ 19 , 21 ], but well characterized in humans with SARS-CoV-2 infection [ 22 , 23 , 24 ].…”

Identification of critical genes and molecular pathways in COVID-19 myocarditis and constructing gene regulatory networks by bioinformatic analysis

“…With the increase in clinical cases [13,14] and reported deaths [15] of SARS-CoV-2 associated respiratory and cardiac complications, people increased interest in COVID-19 Myocarditis. However, in clinical practice, the diagnosis of COVID-19 Myocarditis is not well established, and the biological pathways associated with the two are not fully understood, which has caused widespread concern in the medical community [16,17].…”