When to perform an echocardiogram in a patient with Methicillin-sensitive Staphylococcus aureus (MSSA) bacteremia?

From the Guidelines

Echocardiography should be performed in all patients with Methicillin-Sensitive Staphylococcus aureus (MSSA) bacteremia to evaluate for infective endocarditis, with transthoracic echocardiography (TTE) as the first-line imaging modality, as recommended by the 2015 ESC guidelines 1. When to perform an echocardiogram in a patient with MSSA bacteremia is a critical decision, as MSSA has a high propensity to cause endocarditis, which can significantly impact morbidity, mortality, and quality of life.

• The initial echocardiogram should be a TTE, ideally within the first few days of diagnosis, to evaluate for signs of endocarditis, such as vegetations, valve dysfunction, or perivalvular complications.
• If the TTE is negative but there is high clinical suspicion for endocarditis, or in patients with risk factors such as prosthetic heart valves, congenital heart disease, previous endocarditis, intravenous drug use, persistent bacteremia (>3 days), or embolic phenomena, a transesophageal echocardiography (TEE) should be performed, as it has higher sensitivity for detecting vegetations and perivalvular complications 1.
• Additionally, echo should be repeated if there is persistent bacteremia despite appropriate antibiotic therapy, new cardiac symptoms develop, or if there are new embolic events, as recommended by the 2011 IDSA guidelines 1. The rationale for obtaining echo in MSSA bacteremia is that early detection of endocarditis through echocardiography helps guide appropriate management, including the duration of antibiotic therapy and the potential need for surgical intervention, ultimately improving outcomes.
• It is essential to note that the 2015 ESC guidelines recommend TTE as the first-line imaging modality, while the 2011 IDSA guidelines prefer TEE over TTE, highlighting the importance of considering the most recent and highest-quality evidence when making clinical decisions 1.

From the FDA Drug Label

Echocardiography, including a transesophageal echocardiogram (TEE), was performed within 5 days following study enrollment. The patient should undergo an echocardiogram within 5 days of being diagnosed with Methicillin-sensitive Staphylococcus aureus (MSSA) bacteremia, as part of the diagnostic workup to assess for possible endocarditis, using the modified Duke criteria 2.

• Key points to consider:
  • Timing: Within 5 days of study enrollment
  • Type of echocardiogram: Transesophageal echocardiogram (TEE) may be performed
  • Purpose: To assess for possible endocarditis using the modified Duke criteria

From the Research

Echocardiogram in MSSA Bacteremia

• The decision to perform an echocardiogram in a patient with Methicillin-sensitive Staphylococcus aureus (MSSA) bacteremia should be based on the patient's risk factors for infective endocarditis (IE) 3, 4, 5, 6, 7.
• Patients with prosthetic heart valves or cardiac rhythm management (CRM) devices should receive early cardiological input and transoesophageal echocardiography (TEE) due to their high risk of developing IE 3, 4.
• Patients with a clearly defined line-related bacteremia who do not have a prosthetic valve or CRM device or clinical features of IE may not require immediate echocardiography, and response to treatment could be closely monitored with imaging deferred 3.
• Patients without a line-related infection or prosthetic valve/device could receive a transthoracic echocardiogram (TTE) as a screening tool 3.
• The presence of underlying valvular heart disease, history of prior endocarditis, intravenous drug use, community acquisition of bacteremia, and unknown portal of entry are risk factors for IE that warrant echocardiography 5.
• Persistent bacteremia (positive blood cultures at day 3 of appropriate therapy) is an independent risk factor for both endocarditis and mortality, and patients with this condition may benefit from more aggressive management, including TEE 5.
• TEE is essential to establish the diagnosis and to detect associated complications of IE, and its use should be considered part of the early evaluation of patients with SAB 6.
• A scoring system, such as the modified Palraj's score, can be used to guide the use of TEE in patients with SAB, taking into account factors such as intravenous drug abuse, cardiac devices, and prolonged bacteremia 7.