Endocarditis

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(Class I)

A general infectious disease workup should be obtained, including complete blood cell count, coagulation studies, blood chemistry studies and metabolic profiles for renal function evaluation, hepatic function panels, venous blood gas, lactate, and—importantly—blood cultures. In cases in which suspicion for endocarditis is high, at least 3 sets of blood cultures, rather than the traditional 2, should be drawn from different venipuncture sites to increase diagnostic yield of bacteremia. An electrocardiogram should be obtained to evaluate for arrhythmias, conduction abnormalities, and for heart block, which potentially herald perivalvular abscesses affecting conduction pathways. There is also potential for concurrent ST-elevation myocardial infarction in endocarditis, with spurring of vegetations into the coronary vasculature.

Troponin testing is useful in assisting with determining the degree of myocardial injury and in diagnosis of concurrent myocardial infarction. Brain natriuretic peptide (BNP) can aid clinical judgment in evaluating for acute decompensated heart failure, and has been demonstrated to correlate with poorer outcomes in active endocarditis. Chest x-ray may help identify infiltrates suspicious for pulmonary emboli, associated pleural or parapneumonic effusions, pulmonary edema, and other complications.

Neuroimaging plays an essential role in the diagnosis and management of all types of stroke. Noncontrast CT of the head is essential in evaluating for ICH in the workup of stroke. Twenty-four-hour capability for noncontrast CT is available in 99% of United States EDs. Generally, ICH is differentiated as primary versus secondary, with primary ICH including potential underlying etiologies such as hypertension-associated ICH and cerebral amyloid angiopathy. Secondary etiologies include underlying vascular malformation, infectious intracranial aneurysm, mass, venous sinus thrombosis, and ischemic stroke hemorrhagic conversion. In IEAS, ICH may be a complication of infectious intracranial aneurysm rupture.

CT angiography (CTA) and magnetic resonance angiography (MRA) of the head and neck play important roles not only in the setting of ICH in endocarditis and evaluation for underlying vascular abnormalities, but also in determining eligibility for mechanical thrombectomy if a large-vessel occlusion is identified. Despite hesitancy due to the potential harm of iodinated contrast and causation of contrast-induced nephropathy, there is little evidence of true causation with contrast administration resulting in clinically significant acute kidney injury in patients with preserved glomerular filtration rates. In patients with suspected stroke, renal function should not prohibit cross-sectional imaging with iodinated contrast.

CT perfusion and MRI with diffusion-weighted imaging offer the ability to assess ischemic penumbra relative to core, known as mismatch, in which mechanical thrombectomy may be indicated for certain subgroups. Contrasted imaging also allows identification of infectious intracranial aneurysms, and if CT venogram is dual-protocoled when performing CTA, septic venous sinus thrombosis may also be investigated. Unfortunately, there are no current guidelines or evidence-based recommendations regarding utilization of perfusion-based imaging in guiding intervention with mechanical thrombectomy in IEAS.