Can transthoracic echocardiography be used to a greater extent in the diagnostics of infective endocarditis to avoid unnecessary transoesophageal examinations without jeopardising accuracy?

Background: Infective endocarditis (IE) is a serious condition that requires prompt diagnosis and treatment. Transthoracic echocardiography (TTE) is usually the initial imaging modality, however transoesophageal echocardiography (TOE) is sometimes necessary because of its higher sensitivity for IE. Yet, TOE may imply an increased risk of complications. This project aims to evaluate whether TTE can be used to a greater extent in the diagnostics of IE to avoid unnecessary TOE examinations without jeopardizing diagnostic accuracy.

Methods: Data from all TOE examinations performed on patients hospitalized with clinical suspicion of IE between 2019-05-01 and 2020-04-30 at a university hospital in Stockholm, Sweden, were obtained and analysed. Variables included for analysis were age, sex, blood culture results, aetiology, results from TOE, number of TOEs during the inclusion period, results from positron emission tomography/computed tomography (PET/CT), new regurgitation, cardiac murmur, previous IE, prosthetic valve, predisposing factors, i.e. cardiac comorbidities, injection drug use, fever, vascular phenomena, and immunological phenomena. To assess associations between predisposing factors or aetiology of IE and TOE findings, chi square tests and logistic regression models were used. For continuous variables, linear regression was used for comparisons of means and quantile regression was used for comparisons of medians. P < 0.05 was considered significant.

Results: In total 195 TOE examinations (Table 1) from 160 patients were included, of which 61 (31%) were positive for IE. In total, 36 examinations had negative TTE prior to TOE of which 32 (86%) also had negative TOE. Of the 5 (14%) negative TTE prior to TOE that had positive TOE, all had cardiovascular implantable electronic device (CIED) and/or prosthetic valves.

Conclusions: The existing recommendations for TOE in patients with clinical suspicion of IE are probably broad enough not to miss patients with IE, but there might be an unnecessarily large number of patients being referred for TOE with negative results. Negative TTE examination with good image quality and no CIED or prosthetic valves, may be sufficient without jeopardizing the IE diagnosis.