**6. Echocardiographic predictors of prognosis**

useful additional information regarding the periannular extent of abscess and the relation to

Three-dimensional imaging enables valve perforations to be viewed 'en face' providing precise localization and sizing of any defect, while a small number of case reports indicate a higher detection rate when compared to 2D TEE [94, 95]. One drawback of 3D is artifactual 'dropout', especially with thin valvular tissue and suboptimal gain settings, which can result in falsepositive findings. To confirm the finding, the defect should be visualized in systole and diastole and associated with a thickened rim surrounding the perforation [96]. Finally, 3D may assist

Three-dimensional TEE has the potential to demonstrate the extent and location of a valve aneurysm with greater accuracy than 2D imaging [97]. Similarly with perivalvular dehiscence, 3D is able to define the anatomic spatial relationship to surrounding structures and accurately define the location, size, and extent of the pathology [93]. One study showed the added benefit of 3D contrast TTE for accurately delineating the size and extent of a left ventricular pseudoa-

The role of 3D echo for right-sided IE is restricted to case reports and small case series [99, 100]. Sungur et al. [101] published the first study that compared 3D versus 2D TEE in tricuspid valve endocarditis against the gold standard of surgery. Three-dimensional imaging provided en-face visualization of all three TV leaflets in nine of 10 cases, allowing accurate identification and localization of multiple vegetations. In addition, 3D was able to better characterize vegetation morphology and size. Three-dimensional TEE also identified a tricuspid annular abscess that was missed on 2D TEE imaging. Three-dimensional TEE may add incremental value in localizing vegetations that are partly obscured by reverberation artifact on 2D imaging [99]. Because the right heart is located anteriorly in the chest, 3D TTE is particularly

Echocardiography, especially TTE, has a number of potential limitations due to patient and nonpatient factors. TTE image quality is influenced by body habitus, chest wall deformity, rib space size, and interposing lung tissue. Poor TTE image quality is the main factor accounting

Furthermore, the skills of the sonographer and echocardiologist also influence diagnostic accuracy as shown by interobserver variability. Clinical history is important to the reporting echocardiographer but may result in bias with a trade-off between sensitivity and specificity

The ultrasound equipment, machine settings, and transducer frequency all impact on diagnostic accuracy. The limits of image resolution allow detection of vegetations down to 1.5–2 and 3–4 mm, for TEE and TTE, respectively. Not surprisingly, it has been shown that smaller

useful and has the potential to provide better imaging of the tricuspid valve.

surrounding anatomical structures, including the coronary arteries [90, 93].

with surgical planning when repair is contemplated [94, 96].

neurysm, when compared to 2D contrast TTE [98].

**5.5. Limitations of echocardiography**

[102, 103].

for the superior diagnostic accuracy of TEE [54].

vegetation size reduces the sensitivity of TTE [54, 104].

*5.4.3. Other complications*

76 Contemporary Challenges in Endocarditis

Embolism occurs in approximately one-quarter to one-half of patients [106, 107] with endocarditis, but the risk is substantially reduced after initiation of antibiotics within the first 1–2 weeks [111, 114]. Large mobile vegetations are associated with more complications. Vegetations >10 mm in length [55, 106, 110] and mobile masses carry the greatest risks of embolism [106, 111, 112].

Vegetations >15 mm and high mobility pose a major risk of systemic embolism [113]. Previous embolism, change in size of vegetations, *S. aureus*, and mitral valve location increase the risk of new embolism [114]. Right-sided vegetations ≥20 mm portend a poor prognosis, with mortality similar to that of left-sided IE [39, 40].

Echocardiography is very useful at identifying important prognostic markers related to extent of infection, cardiac function, and hemodynamics. Predictors of outcome include periannular extension, severe valvular dysfunction, left and right ventricular systolic function, left atrial size, left ventricular size, left ventricular filling pressures, and pulmonary artery pressure [1, 110, 115, 116]. More specifically, in left-sided native valve *S. aureus* endocarditis, an LVEF <40% or presence of abscess independently predicts in-hospital mortality while abscess and leaflet perforation both independently predict 12-month mortality [117].
