ABSTRACT
ImportanceAcute COVID-19-related myocardial, pulmonary and vascular pathology, and how these relate to each other, remains unclear. No studies have used complementary imaging techniques, including molecular imaging, to elucidate this. ObjectiveWe used multimodality imaging and biochemical sampling in vivo to identify the pathobiology of acute COVID-19. Design, Setting and ParticipantsConsecutive patients presenting with acute COVID-19 were recruited during hospital admission in a prospective cross-sectional study. Imaging involved computed-tomography coronary-angiography (CTCA - identified coronary disease), cardiac 2-deoxy-2-[fluorine-18]fluoro-D-glucose positron-emission tomography/computed-tomography (18F-FDG-PET/CT - identified vascular, cardiac and pulmonary inflammatory cell infiltration) and cardiac magnetic-resonance (CMR - identified myocardial disease), alongside biomarker sampling. ResultsOf 33 patients (median age 51 years, 94% male), 24 (73%) had respiratory symptoms, with the remainder having non-specific viral symptoms. Nine patients (35%, n=9/25) had CMR defined myocarditis. 53% (n=5/8) of these patients had myocardial inflammatory cell infiltration. Two patients (5%) had elevated troponin levels. Cardiac troponin concentrations were not significantly higher in patients with myocarditis (8.4ng/L [IQR 4.0-55.3] vs 3.5ng/L [2.5-5.5], p=0.07) or myocardial cell infiltration (4.4ng/L [3.4-8.3] vs 3.5ng/L [2.8-7.2], p=0.89). No patients had obstructive coronary artery disease or vasculitis. Pulmonary inflammation and consolidation (percentage of total lung volume) was 17% (IQR 5-31%) and 11% (7-18%) respectively. Neither were associated with presence of myocarditis. Conclusions and relevanceMyocarditis was present in a third patients with acute COVID-19, and the majority had inflammatory cell infiltration. Pneumonitis was ubiquitous, but this inflammation was not associated with myocarditis. The mechanism of cardiac pathology is non-ischaemic, and not due to a vasculitic process. Key PointsO_ST_ABSQuestionC_ST_ABSWhat is the pathobiology of the cardiac, pulmonary and vascular systems during acute COVID-19 infection ? FindingsOver a third of patients with acute COVID-19 had myocarditis by cardiac MRI criteria. Myocardial inflammatory cell infiltration was present in about two thirds of patients with myocarditis. No associations were observed between the degree of pulmonary involvement and presence of myocarditis. There was no evidence of obstructive coronary artery disease or evidence of large vessel vasculitis. MeaningMyocarditis is common in acute COVID-19 infection, and may be present in the absence of significant pulmonary involvement. The cause of myocarditis is inflammatory cell infiltration in the majority of cases, but in about a third of cases this is not present. The mechanism of cardiac pathology in acute COVID-19 is non-ischaemic, and vascular thrombosis in acute COVID-19 is not due to significant coronary artery disease or a vasculitic process.
