[ANMCO Position paper: Pulmonary circulation diseases and COVID-19].

The new coronavirus disease 2019 (COVID-19), which is causing hundreds of thousands of deaths worldwide, is complex and can present with a multi-organ localization. One of its worst complications is an interstitial pneumonia with acute respiratory failure also known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which requires non-invasive or invasive ventilation. A severe coagulopathy with poor prognosis is found in 5-10% of cases. SARS-CoV-2 is manifesting as a multi-dimensional disease and, recently, unique co-existing pathophysiological and clinical aspects are being defined: (i) an increased immune and inflammatory response with the activation of a cytokine storm and consequent coagulopathy, which promote both venous thromboembolic events and in situ thrombosis localized in small arterioles and pulmonary alveolar capillaries; (ii) a high intrapulmonary shunt, which often accounts for the severity of respiratory failure, due to reduced hypoxic pulmonary vasoconstriction with pulmonary neo-angiogenetic phenomena. Furthermore, the high incidence of venous thromboembolism in COVID-19 patients admitted to the intensive care unit and the autoptic findings of in situ micro-thrombosis at the pulmonary vascular level, suggest that in this disease coagulopathy, unlike septic disseminated intravascular coagulation, is driven towards a hyper-thrombogenic state, giving rise to a debate (with ongoing studies) about the preventive use of anticoagulant doses of heparin to reduce mortality. The aim of this position paper from the Italian Association of Hospital Cardiologists (ANMCO) is to highlight the main implications that COVID-19 infection has on the pulmonary circulation from a pathophysiological, clinical and management point of view.