Retrospective Study
Copyright ©The Author(s) 2019. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Cardiol. Feb 26, 2019; 11(2): 84-93
Published online Feb 26, 2019. doi: 10.4330/wjc.v11.i2.84
Prevalence and clinical characteristics associated with left atrial thrombus detection: Apixaban
Hoyle L Whiteside, Arun Nagabandi, Kristen Brown, Deepak N Ayyala, Gyanendra K Sharma
Hoyle L Whiteside, Kristen Brown, Division of Internal Medicine, Medical College of Georgia at Augusta University, Augusta, GA 30912, United States
Arun Nagabandi, Gyanendra K Sharma, Division of Cardiology, Medical College of Georgia at Augusta University, Augusta, GA 30912, United States
Deepak N Ayyala, Division of Biostatistics and Data Science, Department of Population Health Sciences, Medical College of Georgia at Augusta University, Augusta, GA 30912, United States
Author contributions: Whiteside HL wrote the manuscript; Whiteside HL, Nagabandi A and Sharma GK reviewed and revised the final version of the manuscript; Whiteside HL, Nagabandi A and Sharma GK designed the study; Whiteside HL, Nagabandi A and Brown K coordinated and provided the data collection; Ayyala DN provided statistical consultation and analysis.
Institutional review board statement: The Institutional Review Board of Augusta University reviewed and approved this study on February 8, 2017.
Informed consent statement: This study was a retrospective analysis utilizing data readily available within the electronic medical record system. The study received a waiver of the consent process upon review by the Institutional Review Board and the dataset was stored electronically on an institutional research drive.
Conflict-of-interest statement: The authors report no financial relationships or conflicts of interest regarding the content.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Corresponding author: Hoyle L Whiteside, MD, Doctor, Division of Internal Medicine, Medical College of Georgia at Augusta University, 1120 15th St., Augusta, GA30909, United States. hwhiteside@augusta.edu
Telephone: +1-706-7212423 Fax: +1-706-7211059
Received: October 24, 2018
Peer-review started: October 24, 2018
First decision: December 10, 2018
Revised: December 18, 2018
Accepted: January 8, 2019
Article in press: January 9, 2019
Published online: February 26, 2019
ARTICLE HIGHLIGHTS
Research background

The prevalence of left atrial appendage (LAA) thrombus detection by transesophageal echocardiogram (TEE) in patients anticoagulated for ≥ 4 wk with apixaban is not well defined and predictors of LAA thrombus detection are not completely understood. Furthermore, the efficacy of apixaban to resolve pre-existing LAA thrombi is not well documented.

Research motivation

Prescriptions rates for non-vitamin K dependent oral anticoagulants are increasing on a yearly basis and further analysis of patients prescribed apixaban could have clinically meaningful implications. We aimed to identify significant predictors of LAA thrombus detection on TEE to aid in the selection process for screening in future patients undergoing direct current cardioversion or catheter ablation.

Research objectives

The purpose of our study was to retrospectively analyze the prevalence of LAA thrombus detection by TEE in patients continuously anticoagulated with apixaban for ≥ 4 wk and evaluate for any cardiac risk factors or echocardiographic characteristics which may serve as predictors of thrombus formation.

Research methods

Clinical and echocardiographic data for 820 consecutive patients with atrial fibrillation (AF) undergoing TEE at Augusta University Medical Center over a four-year period were retrospectively analyzed. All patients (apixaban: 226) with non-valvular AF and documented compliance with apixaban for ≥ 4 wk prior to index TEE were included.

Research results

Following ≥ 4 wk of continuous anticoagulation with apixaban, the prevalence of LAA thrombus and LAA thrombus/dense spontaneous echocardiographic contrast was 3.1% and 6.6%, respectively. Persistent AF, left ventricular ejection fraction < 30%, severe LA dilation, and reduced LAA velocity were associated with thrombus formation. Following multivariate logistic regression, persistent AF (OR: 7.427; 95%CI: 1.02 to 53.92; P = 0.0474), and reduced LAA velocity (OR: 1.086; 95%CI: 1.010 to 1.187; P = 0.0489) were identified as independent predictors of LAA thrombus. No Thrombi were detected in patients with a CHA2DS2-VASc score ≤ 1.

Research conclusions

Among patients with non-valvular AF and ≥ 4 wk of anticoagulation with apixaban, the prevalence of LAA thrombus detected by TEE was 3.1%. This suggests that continuous therapy with apixaban does not completely eliminate the risk of LAA thrombus and that TEE prior to cardioversion or catheter ablation may be of benefit in patients with multiple risk factors.

Research perspectives

Compliance with non-vitamin K oral anticoagulants reduces but does not eliminate the prevalence of thrombus detection by TEE. However, available cost-effectiveness analysis reports that pre-procedural TEE is unlikely to be cost-effective in an unselected population. Therefore, there is a need to better identify patients with increased pretest probability of LAA thrombus in order to improve the cost-benefit ratio of the procedure. It is our hope that identification of additional clinical and echocardiographic characteristics; in addition to established risk factors, can help guide the selection process for utilization of pre-procedural TEE