Left Atrial Imaging Prior to Cardioversion: Leveraging Computed Tomography to Rule Out Thrombus

Contrast enhanced ECG-gated cardiac CT (CCT) is a sensitive, noninvasive alternative method used to exclude of left atrial and LAA thrombus. CCT provides high spatial and good temporal resolution and its ability to detect thrombus has been evaluated. CCT, compared to TEE, for the exclusion of thrombus in the LAA had a sensitivity and specificity of 100% and 99.3%, respectively. A high sensitivity is needed to minimize risk of embolus, and if a thrombus is detected on CT, a confirmatory TEE may be performed or patients may receive anticoagulation. Some argue that the potential benefits of CT and its lower associated procedural risk, the risk:benefit ratio would still favour CT.

TEE is considered the reference standard to rule-out left atrial (LA) and left atrial appendage (LAA) thrombus prior to cardioversion. Several studies have examined the accuracy of TEE for detecting LAA thrombus. Compared to autopsy and intraoperative findings, TEE has a mean sensitivity of 100% and mean specificity of 99%. Although the gold standard, a TEE-guided therapy is still associated with an embolic rate of 0.8%.