**8. Miscellaneous considerations**

During the past two decades, significant increases have been noted in the number of valvular repairs, valve replacements, intracardiac devices and hemodialysis catheter placements [125–128]. Collectively, these procedures inherently create a small, but significant risk of IE, especially in patients with chronic comorbid conditions such as renal insufficiency, diabetes and autoimmune diseases [129–131]. Given the potential for major morbidity and mortality associated with IE in the setting of indwelling intravascular/intracardiac devices, the primary focus should be on prevention. Within this context, efforts include more selective device implantation policies and better modulation of known post-implantation risks [132].

In terms of general diagnostic considerations, numerous guidelines and recommendations have been published to date. Although beyond the scope of the current discussion, certain aspects of these recommendations warrant a brief mention [133, 134]. One very important highlight is the emphasis on prompt echocardiography in cases of suspected IE, with TEE recommended if the initial TTE is negative and clinical suspicion remains high [8]. Echocardiographic imaging can then be repeated in 3–5 days if clinical symptoms/suspicion persist [8]. It is also suggested that patients with vegetations >10 mm in size, embolic events while on antibiotic treatment, and patients with >2 embolic events should be evaluated for surgical intervention [8]. One unique diagnostic consideration is the inability to use magnetic resonance imaging (MRI) in patients with certain types of intravascular devices/implants. Amraoui et al. recently described the use of positron emission tomography (PET) as an alternative method of identifying foci of SE in patients with implantable cardiac devices, with limited success [135].

Treatment options start with intravenous antibiotics, however in certain cases prompt surgical treatment is necessary. The American Heart Association developed guidelines to assist with identification of patients who require prompt surgical intervention [136]. Patients with IE who develop decreased left ventricular ejection fraction (LVEF) or a new aortic or mitral valve murmur require prompt surgery [50, 136, 137]. Patients with preserved LVEF that are stable and adequately managed on medical therapy do not need an immediate corrective surgery [138]. However, a recent study demonstrated that surgical intervention in the setting of CHF can reduce mortality from approximately 60–85% to 15–35% when compared to medical therapy alone [139, 140]. Patients who present with valvular vegetations >10 mm in size, or with multiple vegetations on imaging, are likely to benefit from surgery [136]. Another important indication for surgery is lack of improvement after 7 days of appropriate antibiotic therapy [136]. Any SE to end organs or associated arterial aneurysms also warrant immediate surgical evaluation and prompt intervention. As mentioned earlier in the chapter, emboli to different anatomic regions may require distinct plans and different timing in terms of surgical intervention [50]. The diagnosis of prosthetic valve endocarditis constitutes another major indication for surgical intervention. Patients who present within 60 days of discharge following the placement of a new prosthetic valve with persistent fevers should be evaluated for the presence of IE, and if proven to harbor such infection should undergo operative management. It is important to remember that roughly 25% of prosthetic valve patients may be at risk of IE [136, 141].
