The risk of transmission of the novel coronavirus (SARS-CoV-2) with human heart valve transplantation: evaluation of cardio-vascular tissues from two consecutive heart donors with asymptomatic COVID-19

We report on two living donors of explanted hearts while receiving heart transplantation that tested positive for SARS-CoV-2 on the day of donation, although clinically asymptomatic. They underwent heart transplantation for ischaemic and hypertrophic obstructive cardiomyopathy, respectively. After evaluation of donor hearts, we cryopreserved and stored two pulmonary valves for clinical application and one aortic valve for research. Light microscopy of myocardium, mitral valve and aortic and pulmonary arterial wall and RT-PCR SARS-CoV-2 test of myocardium, mitral and tricuspid valve and aortic wall for detection of SARS-CoV-2 were performed. Presence of ACE2 in tissues was assessed with immunostaining. Light microscopy revealed a mild eosinophilic myocarditis in the ischemic cardiomyopathy heart, whereas enlarged cardiomyocytes with irregular nucleus and some with cytoplasmic vacuoles in the hypertrophic obstructive cardiomyopathy heart. Aortic and pulmonary wall were histologically normal. Immunostaining revealed diffuse presence of ACE2 in the myocardium of the heart with eosinophilic myocarditis, but only discrete presence in the hypertrophic cardiomyopathy heart. The RT-PCR SARS-CoV-2 test showed no presence of the virus in tested tissues. Despite eosinophilic myocarditis in the ischemic cardiomyopathy heart, no viral traces were found in the myocardium and valve tissues. However, ACE2 was present diffusely in the ischemic cardiomyopathy heart. SARS-CoV-2 could not be detected in the cardiac tissues of these COVID-19 asymptomatic heart donors. In our opinion, clinical application of the valves from these donors presents negligible risk for coronavirus transmission. Nonetheless, considering the uncertainty regarding the risk of virus transmission with the human tissue transplantation, we would not release in any case the pulmonary valve recovered from the eosinophilic myocarditis heart. In contrast, we may consider the release of the pulmonary valve from the dilated cardiomyopathy heart only for a life-threatening situation when no other similar allograft were available.