Management of Gram-Negative Bacteremia in Patients with Pacemakers

Indications for Transesophageal Echocardiography (TEE)

The American Heart Association recommends TEE when clinical suspicion of infective endocarditis (IE) remains high despite negative or nondiagnostic transthoracic echocardiography (TTE), particularly in patients with prosthetic heart valves, new atrioventricular block or conduction abnormalities, persistent fever despite appropriate antibiotics, new valvular regurgitation or heart failure, or embolic phenomena 1, 2
TEE is indicated in patients with gram-negative bacteremia and a pacemaker if there are specific high-risk features suggesting IE, such as new heart murmur, embolic phenomena, or persistent fever >72 hours on appropriate antibiotics 1, 4

The European Society of Cardiology and the American Heart Association recommend starting with TTE in all suspected IE cases, as it is the recommended first-line test, with a sensitivity of 60-70% for native valve endocarditis but only 25-40% for device-related infections 1, 3, 4
Proceed to TEE if TTE is negative but clinical suspicion remains high, or if TTE is positive but complications need assessment, given that TEE sensitivity for device infections is approximately 90% compared to 25-40% for TTE 1, 3, 5

In patients with gram-negative bacteremia and a pacemaker, proceed to TTE if any of the following are present: no identifiable source of bacteremia, generator pocket signs of infection, new heart murmur, embolic phenomena, or persistent fever >72 hours on appropriate antibiotics 1, 4
Repeat TEE in 3-5 days if clinical suspicion persists despite negative initial TEE, as early vegetations may be too small or abscesses may appear only as nonspecific thickening initially 1, 6

Intracardiac abscess detected on echocardiography independently predicts both in-hospital and 1-year mortality, highlighting the importance of accurate diagnosis and management 6