A comparison of intracardiac and transesophageal echocardiography to detect left atrial appendage thrombus in a swine model

Transesophageal echocardiography (TEE) is the gold standard in the evaluation for left atrial appendage (LAA) thrombus in patients with atrial fibrillation (AF) and is often performed prior to AF ablation. We routinely use intracardiac echocardiography (ICE) to assist in AF ablation; however, standard right atrial views do not provide adequate visualization of the LAA. As the incidence of thrombus in this population is relatively low, TEE incurs additional risk, cost, and patient discomfort. Novel views of the LAA with ICE may obviate the need for TEE in this population. We tested the hypothesis that due to their proximity, imaging the LAA from the pulmonary artery (PA) would provide equivalent sensitivity and specificity to TEE in detecting LAA thrombus in a swine model.

Five domestic swine were utilized. Baseline images of the LAA with TEE were obtained. An 8Fr ICE catheter was placed in the left main PA, and imaging of the LAA was repeated. After transseptal puncture, an admixture of 2 cm³ blood and 1,000 IU of thrombin was injected into the LAA, and imaging of the LAA was repeated. Two blinded, independent reviewers experienced in ICE assessed the images and adjudicated both the presence of thrombus and the subjective image quality.

The presence or absence of thrombus was correctly identified in all cases by both reviewers. Both reviewers rated the subjective quality of ICE images superior to TEE.

ICE is equivalent to TEE in imaging LAA thrombus in a porcine model. Whether ICE can provide similar diagnostic accuracy and safety for detecting LAA thrombus in humans remains unproven.