This prospective study aims to investigate the association between pericardial histopathologic inflammation grades (acute, chronic, or absent) and COVID-19 seropositivity in adult patients undergoing first-time isolated coronary artery bypass grafting (CABG). Pericardial tissue samples were collected during surgery and evaluated histopathologically, while preoperative COVID-19 serological testing was performed. The primary outcome is to determine whether COVID-19 seropositivity is associated with the severity of pericardial inflammation. Patients with prior cardiac surgery, active COVID-19 infection, systemic inflammatory diseases, chronic immunosuppressive therapy, or malignancy were excluded from the study.

Inclusion Criteria:

• Age ≥20 years
• Undergoing first-time isolated coronary artery bypass grafting (CABG)
• Availability of pericardial tissue sample for histopathological analysis
• Preoperative COVID-19 serological testing performed
• Written informed consent obtained

Exclusion Criteria:

• Previous history of cardiac surgery (e.g., prior CABG, valve surgery)
• Concomitant cardiac procedures during the same operation (e.g., valve repair, aortic surgery)
• Active COVID-19 infection at the time of surgery (positive PCR test)
• Known autoimmune or systemic inflammatory diseases (e.g., lupus, rheumatoid arthritis)
• Chronic immunosuppressive therapy (e.g., steroids, biologics)
• Known malignancy at the time of surgery

Insufficient or inadequate pericardial tissue sample for histopathological assessment

This study included adult patients (≥20 years) undergoing first-time isolated coronary artery bypass grafting (CABG). All patients had available pericardial tissue samples for histopathological evaluation and preoperative COVID-19 serological testing. Patients with prior cardiac surgery, active COVID-19 infection, systemic inflammatory diseases, chronic immunosuppressive therapy, or malignancy were excluded.