In our opinion there are some issues in the present experience that deserve consideration: (1) although active drug addiction is a strong risk factor, native PV endocarditis, especially without TV involvement, is an extremely rare entity (incidence of nearly 1%). (2) The association between active endocarditis and Covid pneumonia is emerging, especially in tertiary hospitals like our center, which during pandemic acted as cardiac surgery hub for the Milan metropolitan area. (3) Covid disease can partially mask subtle endocarditis signs and symptoms, considering that some diagnostic tools are underused for safety reasons and that Covid-19 therapies, like corticosteroids, can worsen septic course of the disease. 4) On the opposite, surgical timing can be difficult to establish in Covid-19 patients, as full sternotomy, coagulation dysregulation and extracorporeal circulation-related inflammatory response can exacerbate ARDS evolution of Covid-19 pneumonia.

The association between infective endocarditis and Covid pneumonia is emerging in the recent months [7]. Although a direct linkage between viral and bacterial etiology cannot be clearly established, some considerations can be ruled out: (1) the reorganization in cardiac surgery hub centers resulted in an increase of urgencies referral, with consequent relative observation of some pathologies (i.e., endocarditis, aortic dissection). (2) The widespread administration of antibiotics and corticosteroids during the first phase of the pandemic could have contributed to the development of a moderate immunodepression of the general population. (3) During the pandemic, patients have been reluctant to access to hospital care, and this diagnostic delay could contribute to misdiagnosis or late presentation.

Patients with active Covid infection and various degrees of respiratory impairment who are referred for urgent cardiac surgery pose unique challenges, especially in determining the correct surgical timing.

Indeed, several reports of emergent cardiac surgery performed in patients affected by Covid pneumonia reported high intraoperative mortality and perioperative respiratory complications. On the contrary, the delay in surgical treatment of patients simultaneously affected by IE and Covid pneumonia can result in catastrophic consequences.