Limitations of rapid serological testing for SARS-CoV-2 in non-vaccinated patients in acute cardiac care

In December 2019 in the city of Wuhan, in China, the first cases of infection caused by the new SARS-CoV-2 virus appeared, and later on, the disease caused by this virus was named COVID-19. Shortly after this, on March 11 th , 2020, the WHO characterized COVID-19 as a global pandemic. The symptoms of COVID-19 and acute cardiovascular disorders (e.g., heart failure, pulmonary embolism or myocardial ischemia) frequently overlap, which poses a challenge for the establishing of a differential diagnosis in clinical practice. Rapid serological tests, which detect IgM and IgG classes of antibodies for SARS-CoV 2, have been developed with the primary purpose of screening the population's immunological response to the SARS-CoV-2 virus. However, rapid serological tests are often used outside their original purpose, i.e., for the triage of possibly infected, non-vaccinated individuals, because they offer quick results, which may be particularly relevant in emergency settings. If serological testing is used to guide the admission of non-vaccinated patients with acute cardiovascular disorders to either an isolation unit for suspected COVID-19 positive individuals, or to hospital facilities for non-infected patients, it is important to recognize its limitations, in order to reduce the risk of false-positive or false-negative results. Hence, appropriate patient selection and cautious test interpretation is necessary to avoid misdiagnosis. The aim of this paper is to illustrate how serological testing may be used as a screening tool to inform the management of non-vaccinated patients with acute cardiovascular disorders requiring urgent hospital admission. As an illustration, we describe two clinical situations, in which serological testing produced meaningful results.