Impact of harmonic imaging on transthoracic echocardiographic identification of infective endocarditis and its complications

Abstract

Objective: To evaluate the comparative diagnostic value of harmonic imaging (HI) in the assessment of patients with suspected infective endocarditis (IE).

Setting: Tertiary referral centre.

Design: 139 consecutive patients were evaluated with three imaging modalities: transthoracic echocardiography with fundamental imaging (FI); HI; and transoesophageal echocardiography (TOE). Image quality was assessed for each modality by semiquantitative scoring (0, poor, to 3, excellent). Presence, dimension, and characteristics of vegetations were assessed separately for each imaging modality, as well as presence of abscesses.

Results: 35 patients had definite IE. TOE was positive in 33 patients, HI in 28, and FI in 12 (p < 0.001 for FI v HI and v TOE). Mean image quality was 1.4 (0.7) for FI, 2.1 (0.6) for HI (p < 0.01 v FI), and 2.6 (0.4) for TOE (p < 0.001 v HI). The association between FI and TOE findings was Phi = 0.35 (chi2 = 17.57, p = 0.0014) and between HI and TOE it was Phi = 0.95 (chi2 = 125.72, p < 0.0001; p < 0.0001 v FI). The global echo score of vegetations was 7.1 (3.3) with FI, 8.5 (3.4) with HI, and 11.3 (3.9) with TOE (p < 0.001 v HI). Compared with TOE, FI identified only one of seven abscesses (sensitivity 14%) and HI identified two of seven abscesses (sensitivity 28%).

Conclusions: HI provides an accurate assessment of suspected IE. TOE achieves superior definition of IE related abnormalities.

Figure 1

Bar graph showing the number of studies concordant with transoesophageal echocardiographic (TOE) findings, according to imaging modality (FI, fundamental imaging; HI, harmonic imaging) and image quality (0–1, poor to moderate image quality; 2–3, good to excellent image quality).

Figure 2

Example of a patient with a vegetation attached to the posterior leaflet of the mitral valve. No valve abnormalities are evident at FI. HI shows an irregularly shaped structure with uneven margins attached to the atrial aspect of the posterior leaflet of the mitral valve (arrow), indicative of vegetation. TOE depicts a large mitral vegetation with an echogenic core and a hypodense surface, attached on the atrial aspect of the posterior mitral leaflet (arrow). AO, aorta; LA, left atrium; LV, left ventricle.

Figure 3

Bar graph showing the echocardiographic characteristics of vegetations assessed by the three imaging modalities. The lines above the bars indicate the standard deviation. *p<0.05 v TOE.