Concealed Left Ventricle to Right Atrium Fistula Complicating Infective Endocarditis

We report a case of aortic prosthetic valve endocarditis presenting with subaortic stenosis without perivalvular leakage and vegetations in the left ventricular outflow and right atrium, the latter being attached to the atrioventricular septum. Intraoperatively, an abscess that had formed on the aortic annulus and perforated to the right atrium was unexpectedly found, the fistula being occluded by vegetations. Even when no left-to-right shunts are detected by imaging, vegetations adjacent to the atrioventricular septum may conceal a left ventricle–right atrium fistula, resulting in prosthetic valve endocarditis presenting clinically as subaortic stenosis without perivalvular leakage.