Prevalence and Cardiopulmonary Characteristics of Post-COVID Syndrome at a Hungarian Tertiary Referral Hospital.

After an acute COVID-19 infection, many patients suffered from various complaints called as post-COVID syndrome. Our post-COVID outpatient department was operational for 19 months, where patients (n = 252) underwent a detailed cardiopulmonary examination within a 3-month-long follow-up period. Most patients (69.9%) had mild acute symptoms with a higher hospitalization risk with preexisting hypertension ( < 0.05) and diabetes ( < 0.001). Most common post-COVID symptoms were fatigue (29.4%) and dyspnea (19.1%). Echocardiographic parameters showed no abnormalities and did not change during the follow-up period. Exercise capacity was also generally normal with no change over time; however, 9.9% of patients showed significant desaturation during a 6 min walk test. This finding showed correlation ( < 0.01) with decreased diffusion capacity (DLCO). Generally, DLCO improved slightly but significantly ( < 0.05) by the end of the follow-up period (from 72.4% to 74.1%). Our key finding was a 10× higher prevalence (24.6%) of lupus anticoagulant positivity among post-COVID patients compared to the normal population (estimated at 2-4%). In conclusion, post-COVID syndrome is a common consequence even after a mild infection. Severe infections tend to lead to worse cardiopulmonary outcomes. Higher prevalence of lupus anticoagulant positivity may underline the importance of autoimmunity in the pathomechanism of post-COVID syndrome.