Cause of death based on systematic post‐mortem studies in patients with positive SARS‐CoV‐2 tissue PCR during the COVID‐19 pandemic

IMPORTANCE: Assessment of the causative association between the COVID‐19 and cause of death has been hampered by limited availability of systematically performed autopsies. We aimed to present autopsy‐confirmed causes of death in patients who died with COVID‐19 and to assess the association between thrombosis and diffuse alveolar damage consistent with COVID‐19 (DAD). METHODS: Consecutive forensic (n = 60) and clinical (n = 42) autopsies with positive post‐mortem SARS‐CoV‐2 PCR in lungs (age 73 ± 14 years, 50% men) were included. The cause of death analysis was based on a review of medical records and histological reports. Thrombotic phenomena in lungs were defined as pulmonary thromboembolism (PE), thrombosis in pulmonary artery branches or microangiopathy in capillary vessels. RESULTS: COVID‐19 caused or contributed to death in 71% of clinical and 83% of forensic autopsies, in whom significant DAD was observed. Of the patients with COVID‐19 as the primary cause of death, only 19% had no thrombotic phenomena in the lungs, as opposed to 38% amongst those with COVID‐19 as a contributing cause of death and 54% amongst patients whose death was not related to COVID‐19 (p = 0.002). PE was observed in 5 patients. Two patients fulfilled the criteria for lymphocyte myocarditis. CONCLUSIONS: Vast majority of all PCR‐positive fatalities, including out‐of‐hospital deaths, during the SARS‐CoV‐2 pandemic were related to DAD caused by COVID‐19. Pulmonary artery thrombosis and microangiopathy in pulmonary tissue were common and associated with the presence of DAD, whilst venous PE was rarely observed. Histology‐confirmed lymphocyte myocarditis was a rare finding.