Afebrile Pannus-Induced Blood Culture–Negative Mechanical Valve Endocarditis

The diagnosis of prosthetic valve endocarditis may be challenging in patients with an atypical clinical presentation. Virtually all infections associated with mechanical prosthetic valves are localized to the prosthesis–tissue junction at the sewing ring and are accompanied by tissue destruction around the prosthesis. Because the orifice of the mechanical prosthetic valve is made of metal and pyrolytic carbon, which do not enable the adherence of microorganisms, any vegetation originating from the interior of the valve orifice is usually rare. Here we present a rare case of pannus-induced mechanical prosthetic valve endocarditis that was difficult to diagnose.