Is Less More? Rationalising the Use of Transthoracic and Transoesophageal Echocardiography in the Investigation of Suspected Endocarditis

Abstract

It is well-established that the sensitivity of transthoracic echocardiography (TTE) in comparison to transoesophageal echocardiography (TOE) in the diagnosis of endocarditis is suboptimal. Our aim was to analyse how much benefit was gained with a guideline-based TTE-first approach. A retrospective analysis was performed of all referrals for TOE at Waikato Hospital containing “?endocarditis” (or similar phrases) received between 1 January 2019–31 December 2019 for patients aged 18 years or older. Diagnostic performance of TOE and TTE were compared with respect to detection of endocarditis. All studies were also evaluated for agreement between TOE and TTE regarding non-valvular findings, specifically left and right ventricular (LV and RV) size and function. Out of 251 TOEs performed in 2019, there were 84 referrals for suspected endocarditis— all of whom received a TTE. In diagnosing endocarditis, compared to TOE, the sensitivity of TTE was 35.3% (12/32), specificity was 94.2% (49/52), positive predictive value (PPV) was 80.0% (12/15) and negative predictive value (NPV) was 69.0% (49/71). In 88.1% (74/84) of cases, there was reasonable inter-investigation agreement (within 5%) for LV and RV function. Our analysis reaffirms that TTE is insensitive in the diagnosis of endocarditis and the majority of TTEs done reveal grossly similar non-valvular findings. Although our analysis is limited by its size, it does raise the question of whether a direct to TOE strategy might provide an earlier definitive diagnosis and avoid unnecessary TTE studies in patients at high risk for endocarditis.Tabled 1Diagnostic Performance of TTE Sensitivity35.3% Specificity94.2% PPV80.0% NPV69.0%Sensitivity by Valve/Site Aortic (n=16)31.3% Mitral (n=18)61.1% Tricuspid (n=2)50.0% Device (n=1)0.0%Sensitivity by Organism S. aureus (n=19)42.1% Viridans Strep (n=5)80.0% Other (n=8)25.0% Open table in a new tab