Abstract
Aorto-atrial fistula is a rare and life-threatening complication of infective endocarditis, classically diagnosed by visualizing a connection between the aorta and atrium with associated continuous flow. A patient presented with bioprosthetic and native valve enterococcal endocarditis with multiple complications, including an aorto-atrial fistula that was diagnosed by color M-mode on transesophageal echocardiography. We review the features of aorto-atrial fistula and utilize this case to demonstrate how M-mode can be leveraged to provide improved temporal resolution in the setting of diagnostic uncertainty.