Examining the Prevalence of Left Atrial Appendage Thrombus in a Cohort of Acute Stroke Patients with an Extended Computed Tomography Angiographic Protocol

Q: What are the key findings of this study?

An extended CTA protocol reliably detected left atrial appendage thrombi in 4.58% of acute stroke patients, with LAA morphology having the highest predictive value for thrombus formation.

Q: What is the clinical evidence from this study?

Study design: Cohort. Population: Acute ischemic stroke (n=240). Intervention: Extended non-gated CTA protocol vs. Conventional CTA protocol. Primary outcome: Prevalence of left atrial appendage (LAA) thrombus.

Szabolcs István Antal; Nikoletta Szabó; Róbert Klucsai; Péter Klivènyi; Zsigmond Tamás Kincses

doi:10.1159/000539170

January 1, 2024European NeurologyOpen Access

Examining the Prevalence of Left Atrial Appendage Thrombus in a Cohort of Acute Stroke Patients with an Extended Computed Tomography Angiographic Protocol

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Key result

Extended carotid CTA detects LAA thrombi in ~5% of acute stroke patients.

n=240

Figures

Why the study?

Routine TTE poorly visualizes the LAA where thrombi commonly occur, while TEE is semi-invasive and time-consuming, prompting evaluation of an extended non-gated carotid CTA protocol to detect LAA thrombi in acute stroke.

Does extending the CTA scan range to include the left atrial appendage reliably detect thrombi in acute stroke patients?

Key Points

To evaluate the prevalence and predictors of left atrial appendage (LAA) thrombi in acute stroke patients using an extended carotid computed tomography angiography (CTA) protocol.
Extended non-gated carotid CTA scans 4 cm below the carina to visualize the left atrium and appendage in 240 acute stroke patients.
Applied extreme gradient-boosting machine learning to identify the top clinical and anatomical predictors of LAA thrombi.
Windsock morphology was the most common shape among patients with thrombi (54.5%), and LAA morphology provided the highest predictive value in gradient-boosting analysis.
Extended CTA scans involved a small but statistically significant increase in radiation dose (1,294.58 ± 192.34 vs. 1,191.6 ± 241.94 mGy*cm², p < 0.001) while detecting thrombi that would have gone untreated by standard echocardiography.

Study Design

Type

Cohort (n=240)

Multicenter

No

Structured PICO

Does extending the CTA scan range to include the left atrial appendage reliably detect thrombi in acute stroke patients?

P

Population

240 adult patients (mean age 71.3 years, 51% female) presenting with acute stroke within 24 hours of symptom onset, evaluated with an extended non-gated CTA protocol.

E

Exposure

Extended non-gated carotid CT angiography (scan range extended 4 cm below the carina to include the left atrium and appendage).

C

Comparator

Conventional CTA protocol starting from the aortic arch (used retrospectively for radiation dose comparison).

O

Outcome

Prevalence of left atrial appendage (LAA) thrombus and identification of clinical predictors of LAA thrombi.surrogate

Extending the non-gated CTA scan range to include the LAA in acute stroke patients provides immediate detection of potential cardioembolic sources in 4.58% of cases, outweighing the minor increase in radiation exposure.

Limitations

Lack of ECG-gating, which hindered image quality by producing motion artifacts.
Single-phase scanning without delayed acquisition, which potentially increased the rate of false positive findings.
No ECG-gating, which could have improved image quality by reducing motion artifacts
Single-phase scans (no delayed acquisition), which might increase the number of false positive filling defects

Implication

Extended CTA may identify LAA thrombi in acute stroke; hypothesis-generating before routine adoption or outcome trials.

Abstract

INTRODUCTION: Current guidelines recommend transthoracic echocardiography (TTE) for routine screening of cardiac emboli; however, the visualization of the left atrial appendage (LAA) where the thrombi are commonly found is poor. Transesophageal echocardiography (TEE) would provide better detectability of LAA thrombus, but it is a time-consuming and semi-invasive method. Extending non-gated carotid computed tomography angiography (CTA) examination to the LAA could reliably detect thrombi and could also aid treatment and secondary prevention of stroke. METHODS: We extended the CTA scan range of acute stroke patients 4 cm below the carina to include the left atrium and appendage. During the review, we evaluated LAA thrombi based on contrast relations. We then used gradient boosting to identify the most important predictors of LAA thrombi from a variety of different clinical parameters. RESULTS: We examined 240 acute stroke patients' extended CTA scans. We detected LAA thrombi in eleven cases (4.58%), eight of them had atrial fibrillation. 23.75% of all patients (57 cases) had recently discovered or previously known atrial fibrillation. Windsack morphology was the most commonly associated morphology with filling defects on CTA. According to the gradient-boosting analysis, LAA morphology showed the most predictive value for thrombi. CONCLUSION: Our extended CTA scans reliably detected LAA thrombi even in cases where TTE did not and showed that 2 patients' LAA thrombus would have been untreated based on electrocardiogram monitoring and TTE. We also showed that the benefits of CTA outweigh the disadvantages arising from the slight amount of excess radiation.

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Cite This Study

Antal et al. (2024) conducted a cohort in Acute ischemic stroke (n=240). Extended non-gated CTA protocol vs. Conventional CTA protocol was evaluated on Prevalence of left atrial appendage (LAA) thrombus. An extended CTA protocol reliably detected left atrial appendage thrombi in 4.58% of acute stroke patients, with LAA morphology having the highest predictive value for thrombus formation.

synapsesocial.com/papers/6a221af1e8ef4064f24ebe05 https://doi.org/10.1159/000539170