Left Atrial Appendage Assessment by CMR
How accurate is cardiac magnetic resonance (CMR) imaging at identifying left atrial appendage (LAA) thrombus?
This retrospective study compared 261 patients undergoing CMR and transesophageal echocardiography (TEE) prior to pulmonary vein isolation procedures, and compared the accuracy of CMR to TEE for identification of LAA thrombus.
Median CHA2DS2-VASc score was 2 and 74% of patients were on anticoagulation. CMR and TEE were performed within 1 ± 2 days. LAA thrombi were reported in nine patients (3.5%) by TEE. In comparison to TEE, the sensitivity and specificity of CMR was 100% and 99% with delayed-enhancement imaging, 67% and 95% for contrast-enhanced magnetic resonance angiography, and 67% and 93% for cine-CMR, respectively.
The authors concluded that CMR has good accuracy to identify LAA thrombus in patients planned for pulmonary vein isolation procedures.
While TEE is commonly performed to evaluate for LAA thrombus in patients planned for atrial ablation procedures, it is an invasive test and typically requires sedation. CMR or computed tomography (CT) are typically used for pulmonary vein mapping, and several studies have reported that CT has excellent accuracy to identify LAA thrombus, particularly when a delayed scan is added to the protocol. A single test that combines both pulmonary vein mapping and LAA assessment would be appealing, as it could lower costs and reduce the number of imaging procedures required. This study reports that CMR can identify LAA thrombus, although this retrospective study includes only a small number of patients with LAA thrombus, and the sensitivity of contrast-enhanced CMR and cine-CMR is limited. Before this can be considered for clinical use, further study is needed that includes a prospective and multicenter design, and examines a larger cohort with a greater number of LAA thrombi.
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