Impact of ultrasound contrast agent on the detection of thrombi during transoesophageal echocardiography

Background: Atrial fibrillation (AF) carries the risk of thrombus formation in the left atrium and especially in the left atrial appendage (LAA). A transoesophageal echocardiography (TOE) is routinely performed in these patients to rule out thrombi before cardioversion or structural interventions like LAA closure or pulmonary vein isolation. However, in a certain number of cases, inconclusive results of the TOE may result. This study was performed to analyse whether the routine use of ultrasound contrast agent (UCA) has an influence on the frequency of thrombus detection.

Methods: In patients with AF who were scheduled for a subsequent interventional procedure, a TOE was initially performed without contrast agent. Then, the TOE was repeated with the use of UCA. The percentage of diagnostic findings regarding the prevalence of thrombus in the LAA with and without UCA were compared (thrombus present (T+), no thrombus (T-) and inconclusive result (T+/-)).

Results: 223 patients were prospectively included into the trial. The numbers of thrombus detection were as follows: without UCA: 17 T+ (7.6%), 154 T- (69.1%), 52 T+/- (23,3%); with UCA: 16 T+ (7.2%), 179 T- (80.3%), 28 T+/- (12.6%; χ²: p<0.01). In 29 examinations (13.0%), the use of UCA had an impact on the subsequent treatment strategy.

Conclusions: The use of UCA during TOE in patients with AF has a significant impact on the subsequent patient management especially due to an improved rule out of LAA thrombi.