Background:Enlarged main pulmonary artery diameter(MPAD)is a predictor of increased mortality in COVID-19. However, the changes in MPAD before and after COVID-19 remain obscure.

Aim:To find the factors that affect changes in MPAD during COVID-19 and postCOVID-19 period; the relationship between the MPAD, thromboinflammation and radiological scores(RS), clinical outcomes in patients.

Methods:This study is retrospective and single centered. Among the 3264 patients hospitalized followed at least 3 months between March 2020 and January 2023, 66 patients with previous and subsequent chest CT were included.3 measurements of MPAD before, during and after COVID-19, WHO Score, RS and laboratory variables have been recorded from the hospital information system. ICU admission and mortality as clinical outcomes and factors that affect MPAD evaluated by uni-and multivariate analysis.

Results:MPAD of patients had increased during COVID-19 and showed tendency to decrease but persisted to increase after(p<0.001,p>0.05). Low Lymphocyte/CRP, high D-dimer and ICU admission had significantly increased risk for remained enlarged MPAD postCOVID-19(OR=10.37,p<0.01;OR=1.1, p<0.01,OR=5.14, p<0.01). Patient with higher postMPAD had significant correlation with increased WHO Score and RS after COVID-19(both R=0.3,p<0.05)but not mortality.

Conclusion:MPAD significantly increases during COVID-19 and persisted after that. Apart from that, patients who admitted to ICU, had high d-dimer and inflammation markers in COVID-19,had increased risk for enlarged postMPAD that correlated WHO-Score and radiological scores in post-COVID-19. Especially these patients, can be followed carefully after the infection.