March 1, 2023Open Access

Diagnosis of left atrial appendage thrombus using cardiac computed tomography: new insights from thrombi locations

Q: What is the clinical evidence from this study?

Study design: Observational. Population: Atrial fibrillation (n=726). Intervention: Cardiac computed tomography (CCT) vs. Transesophageal echocardiography (TEE). Primary outcome: Overall sensitivity of CCT for detecting LAA thrombi.

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Key result

Cardiac computed tomography with a 30-second delayed scan had an overall sensitivity of 68.4% for detecting left atrial appendage thrombi, with significantly lower sensitivity for ostial thrombi (48.3%) versus those inside the appendage (89.3%).

Why the study?

Cardiac computed tomography is an emerging modality for assessing left atrial appendage thrombus, but previous results have been conflicting.

Does cardiac computed tomography accurately detect left atrial appendage thrombus compared to transesophageal echocardiography in patients undergoing catheter ablation for atrial fibrillation?

Study Design

Type

Observational (n=726)

Blinding

Blinded readers

Multicenter

Structured PICO

Does cardiac computed tomography accurately detect left atrial appendage thrombus compared to transesophageal echocardiography in patients undergoing catheter ablation for atrial fibrillation?

Population

726 patients (mean age 61 years, 39.8% female) with atrial fibrillation who underwent both transesophageal echocardiography and cardiac computed tomography before catheter ablation.

Exposure

Cardiac computed tomography (CCT) using a third-generation dual-source CT, consisting of one angiographic phase and one delayed-phase acquisition at 30 seconds after contrast injection.

Comparator

Transesophageal echocardiography (TEE) as the reference standard.

Outcome

Diagnostic accuracy (sensitivity and specificity) of CCT for detecting left atrial appendage (LAA) thrombus.surrogate

CCT with a 30-second delay scan is insufficiently sensitive to reliably exclude LAA thrombi, particularly small, highly mobile thrombi located at the LAA ostium, in patients scheduled for AF ablation.

Limitations

Retrospective single-center study design
CCT protocol contained only one delayed-phase scan
Unaccounted factors such as heart rhythm, atrial/ventricular rate, and blood pressure during imaging
Up to 12-hour interval between TEE and CCT could allow thrombus formation or resolution
Higher incidence of LAA thrombus than previous studies may affect generalizability
Retrospective single-center study limited to patients undergoing catheter ablation for AF
Up to 12-hour interval between TEE and CCT allowing potential thrombus formation or resolution
Higher incidence of LAA thrombus than previous studies, potentially affecting thrombus location and motility

Implication

Delayed CCT lacks sensitivity to exclude LAA thrombi pre-ablation, especially ostial; leaves open optimized protocols versus TEE.

Abstract

Background Cardiac computed tomography (CCT) is an emerging non-invasive modality for assessing left atrial appendage (LAA) thrombus, but the results were conflicting. Our study aims to evaluate the accuracy of CCT for detecting LAA thrombus in patients undergoing catheter ablation of atrial fibrillation (AF), using transesophageal echocardiography (TEE) as the reference standard. Methods From May 2017 to December 2022, 726 patients (male: 60.2%, age: 61±11 years) who had both TEE and CCT before catheter ablation of AF were retrospectively included. The CCT protocol consisted of one angiographic phase and one delayed scan 30 seconds later. LAA thrombi were defined as solid masses on TEE or persistent defects on CCT. The thrombus dimension and location, the LAA filling and emptying flow velocity were assessed by TEE. Results Of the 57(7.9%) patients with LAA thrombi identified by TEE, 29(50.9%) were located at the LAA ostium, and 28(49.1%) were in the LAA. The former showed higher motility following blood flow and heartbeats than the latter. The CCT detected 14(48.3%) of the LAA-ostium thrombi but 25(89.3%) of those in the LAA ( p = 0.001). The LAA-ostium thrombi with the LAA mean flow velocity higher than 0.35m/s and maximum diameters shorter than 10mm were more prone to have CCT false-negative results. Conclusion For patients undergoing catheter ablation for AF, CCT with a 30s delay scan is less sensitive to LAA thrombi than TEE, especially LAA-ostium thrombi with smaller sizes and higher LAA flow velocity. Clinical perspective section What are new? Over half of the LAA thrombi were located at the LAA ostium. The CCT was less sensitive to the LAA-ostium thrombi with smaller sizes and higher LAA flow velocity. What is the clinical implication? 1. The CCT using a 30s delay scan did not reliably exclude the LAA thrombi for the patients scheduled for pulmonary vein isolation, especially those located at the LAA ostium.

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Cite This Study

Guo et al. (2023) conducted an observational in Atrial fibrillation (n=726). Cardiac computed tomography (CCT) vs. Transesophageal echocardiography (TEE) was evaluated on Overall sensitivity of CCT for detecting LAA thrombi. Cardiac computed tomography with a 30-second delayed scan had an overall sensitivity of 68.4% for detecting left atrial appendage thrombi, with significantly lower sensitivity for ostial thrombi (48.3%) versus those inside the appendage (89.3%).

synapsesocial.com/papers/6a221af1e8ef4064f24ebe07 https://doi.org/10.1101/2023.02.24.23286435