4. Diagnosis

While it is often believed that positive blood cultures are the sine qua non in the diagnosis of endocarditis, it must be recognized that patients can often present with extensive destruction, and involvement of their cardiac structures has negative cultures. The original Duke Criteria has for many years provided the foundation for the diagnostic criteria of endocarditis [17]. However, advances in imaging technology and broader application of such technology have also proven to be extremely useful in the management of infected patients and guiding therapy [18]. Historically, transthoracic and transesophageal imaging were considered and still are first-line diagnostic tests to evaluate patients with suspected endocarditis—and current guidelines and appropriateness criteria continue to support their liberal use [2, 12]. The role of other imaging modalities, such as 3D echocardiography, computed tomography (CT), magnetic resonance imaging, and positron-emission tomography (PET) is expanding [19, 20]. Furthermore, not only is early use of advanced imaging well established in the diagnosis and management of endocarditis; it is clear that there should be a low threshold for repeat imaging to follow the response to medical therapies or, more specifically, help identify those patients who are failing medical therapy and might benefit from surgical intervention.
