Ascending Aortic Graft Anastomotic Thrombosis Mimicking Prosthetic Graft Endocarditis

Thrombosis at an ascending aortic graft anastomosis is uncommon and can mimic prosthetic graft endocarditis. A 42-year-old male with bicuspid aortic valve disease status post mechanical aortic valve replacement and ascending aortic graft repair for aneurysmal disease presented for evaluation of recurrent arterial thromboembolic events and concern for prosthetic material complications. Transesophageal echocardiography demonstrated a highly mobile mass at the distal graft anastomosis, while the mechanical valve appeared structurally normal with no vegetation. Computed tomography angiography localized an irregular intraluminal lesion to the distal anastomotic suture line. Surgical exploration revealed an organized, calcified mass that was resected. Blood cultures obtained before antibiotics remained negative, and repeat blood cultures were also negative. Intraoperative tissue cultures, including bacterial, fungal, and acid-fast cultures, were negative, and histopathology showed an organized thrombus with dystrophic calcification and inflammation without microorganisms on special stains. Targeted serological testing and tissue molecular testing were not performed. The multidisciplinary review concluded that the findings were most consistent with anastomotic thrombosis rather than active prosthetic graft endocarditis, and empiric antibiotics were discontinued; however, culture-negative endocarditis was not fully excluded because targeted serological and molecular testing were not performed, and the sterile designation therefore remains presumptive.