What risk of endocarditis is low enough to justify the omission of transoesophageal echocardiography in Staphylococcus aureus bacteraemia? A narrative review

Background: Recent criteria which can identify patients with Staphylococcus aureus bacteraemia (SAB) who are at very low risk of endocarditis raise the question of whether transoesophageal echocardiography (TOE) is appropriate for these patients.

Aims: To estimate the probability of occult endocarditis complicating SAB below which a TOE-guided treatment strategy no longer offers the best 180-day survival, and to examine the key uncertainties affecting this result.

Sources: Estimates of the parameters required to calculate the Pauker-Kassirer testing threshold were identified from studies published prior to 1 June 2017 using a composite search strategy that involved a systematic search for relevant controlled trials and guidelines, followed by a non-systematic iterative search of the observational literature.

Content: Estimates of the necessary parameters were generally consistent across the literature with the exception of the procedural mortality of TOE. In our base-case scenario (TOE mortality 0.1%), the testing threshold for TOE in apparently uncomplicated SAB was a 1.1% probability of occult endocarditis. Sensitivity analyses revealed that the procedural mortality of TOE was a key uncertainty affecting estimates of the testing threshold.

Implications: None of the available clinical tools can place patients with SAB below this probability of endocarditis with 95% confidence. Future work in this area should concentrate on improving the precision of these tools and on exploring the value of alternative echocardiography strategies. In addition, a better understanding of the harms of TOE is required to ensure that recommendations regarding the role of this investigation in the management of patients with SAB are appropriate.