Abstract 2412: Multidetector Computed Tomography For the Identification of Left Atrial Thrombus in Patients Undergoing Pulmonary Vein Isolation
Background Prior to pulmonary vein isolation for treatment of atrial fibrillation, multidetector computed tomography (MDCT) and transesophageal echocardiography (TEE) are often performed. The former is to identify pulmonary vein topography while TEE is used to evaluate for the presence of left atrial thrombus. Whether MDCT can also identify atrial thrombus and provide a substitute for TEE is unknown.
Methods Pts undergoing 64-slice MDCT (GE Lightspeed VCT) and TEE prior to pulmonary vein isolation were studied for left atrial appendage thrombus (LAAT). MDCT diagnosis of LAAT was based on anatomic (contrast filling defect) and tissue characterization criteria (Hounsfield unit density 50–100). TEEs were scored for LAAT [thrombus and thrombus-in-formation (spontaneous echo contrast that failed to clear)] and ostial appendage pulsed wave Doppler (PWD) velocities (>50cm/s considered normal; <50cm/s considered low). All studies were reviewed blinded to the results of the other modality.
Results 42 consecutive pts (57 ± 10 yr, 74% male, 76% paroxysmal AF) underwent MDCT and TEE. 4 pts were identified with LAAT by TEE; all were detected by MDCT . One additional pt had LAAT by MDCT undetected by TEE (interval=0 days) which appeared as a laminar filling defect that preserved the overall contour of the LAA (Figure 1⇓). LAAT by MDCT trended towards association with reduced LAA PWD (p=0.06).
Conclusions MDCT accurately identifies LAAT evidenced by TEE. These data suggest that MDCT may serve as an alternative imaging modality for the evaluation of the left atrial thrombus in patients undergoing AF ablation.