Adding or selecting imaging modalities for incremental diagnosis: a case study of ¹⁸FDG PET/CT in prosthetic valve endocarditis.

ccurate diagnosis of prosthetic heart valve infection has major implications on patient management and outcome. If the presence of prosthetic or periprosthetic valve endocarditis is misclassified, it can lead to delayed antibiotic or surgical intervention, which may adversely affect patient outcomes, and that is not inconsequential. Prosthetic valve endocarditis constitutes up to 30% of all cases of infective endocarditis in developed countries, and the frequency is greatest during the initial 6 months after valve surgery. The in-hospital mortality among patients with prosthetic valve endocarditis can be as high as 47%, particularly for Staphylococcus aureus endocarditis. Although the diagnosis of infectious endocarditis is usually initiated by clinical suspicion, increased inflammatory biomarkers, and positive blood cultures, accurate localization of infection at the prosthetic valve site is accomplished by imaging, primarily with transesophageal echocardiography.However, in nearly 10% to 20% of instances, blood cultures or transesophageal echocardiographic results are inconclusive, thus leading to a high proportion of unconfirmed cases of suspected prosthetic valve endocarditis. Delay in initiating antibiotic treatment can lead to untoward structural damage beyond the prosthesis itself, which may cause acute heart failure as well as systemic complications, such as embolism and cerebral hemorrhage. Unlike the native valve, prosthetic valve endocarditis commonly extends beyond the valve ring into the annulus and periannular and myocardial tissue, causing dehiscence of the prosthesis with significant hemodynamic and conduction disturbances. On histological examination, infected mechanical valves exhibit neutrophil-rich inflammatory infiltrates with