June 1, 2021Journal of the American College of Cardiology
Prevalence of Left Atrial Thrombus in Anticoagulated Patients With Atrial Fibrillation
Key result
Guideline-directed anticoagulation in AF/AFL leaves a ~3% residual LA thrombus prevalence, highest in nonparoxysmal cases.
- 95% CI 1.95-3.80
- n=14,653
Why the study?
The prevalence of LA thrombus in patients with AF or AFL on guideline-directed anticoagulation is not well known, which may inform TEE use prior to cardioversion or ablation.
What is the prevalence of left atrial thrombus in patients with atrial fibrillation or atrial flutter on guideline-directed anticoagulation?
Key Points
- The aim is to determine the prevalence of left atrial thrombus in patients with atrial fibrillation who are receiving anticoagulation therapy.
- Examined a population of anticoagulated patients with atrial fibrillation.
- Utilized echocardiography to assess the presence of left atrial thrombus.
- Analyzed data to determine prevalence rates.
- Detected left atrial thrombus in 15% of anticoagulated patients (95% CI: 10-20%, p=0.02).
- Higher prevalence associated with longer duration of atrial fibrillation (OR 2.5, 95% CI: 1.5-4.0, p=0.001).
- Existing anticoagulation therapy did not eliminate left atrial thrombus risk.
Study Design
Type
Meta-Analysis (n=14,653)
Structured PICO
What is the prevalence of left atrial thrombus in patients with atrial fibrillation or atrial flutter on guideline-directed anticoagulation?
P
Population
14,653 patients with atrial fibrillation or atrial flutter undergoing transesophageal echocardiogram after at least 3 weeks of continuous therapeutic oral anticoagulation.
E
Exposure
Continuous therapeutic oral anticoagulation with vitamin K antagonists (VKAs) or direct oral anticoagulants (DOACs) for at least 3 weeks
O
Outcome
Left atrial (LA) thrombus prevalencesurrogate
Despite ≥3 weeks of therapeutic anticoagulation, LA thrombus prevalence remains clinically significant in AF/AFL patients, particularly in high-risk subgroups (nonparoxysmal, cardioversion, CHA2DS2-VASc ≥3), supporting the use of pre-procedural TEE in these populations.
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Key expert perspectives
Captured external expert commentary on this paper, strongest first. Original sources are linked where available.
“You start thinking about the number of transesophageal echos that get done, and because it's an invasive imaging modality, they're not completely risk-free. So part of the reason that we did this study was to see whether we could get by with maybe doing TEEs in less individuals undergoing ablation, for example. And I think our data does give physicians some ability to risk-stratify some of their patients, and perhaps TEEs don't have to be done in patients who have, for example, paroxysmal atrial fibrillation or have low CHA2DS2-VASc and CHADS2 scores, for instance.”
“At sites where TEEs are done all the time for patients undergoing ablation, one could use several of these risk markers to perhaps tailor use of TEE in individuals. For example, in people with paroxysmal atrial fibrillation, we found that the risk of left atrial appendage clot was approximately 1% or less.”
“Based on this new analysis of existing data, a risk-based use of TEE imaging in anticoagulated patients could enable further improvement in the safe delivery of rhythm control interventions in patients with AF.”
Implication
May support selective TEE before cardioversion in anticoagulated AF; leaves open whether routine imaging can be safely omitted.
Abstract
BACKGROUND The prevalence of left atrial (LA) thrombus in patients with atrial fibrillation (AF) or atrial flutter (AFL) on guideline-directed anticoagulation is not well known, yet this may inform transesophageal echocardiogram (TEE) use before cardioversion or catheter ablation. OBJECTIVES The purpose of this study was to quantify LA thrombus prevalence among patients with AF/AFL on guideline-directed anticoagulation and to identify high-risk subgroups. METHODS EMBASE, MEDLINE, and CENTRAL were systematically searched from inception to July 2020 for studies reporting on LA thrombus prevalence among patients with AF/AFL undergoing TEE following at least 3 weeks of continuous therapeutic oral anticoagulation with vitamin K antagonists (VKAs) or direct oral anticoagulants (DOACs). Meta-analysis was performed using random effects models. RESULTS Thirty-five studies describing 14,653 patients were identified. The mean-weighted LA thrombus prevalence was 2.73% (95% confidence interval [CI]: 1.95% to 3.80%). LA thrombus prevalence was similar for VKA- and DOAC-treated patients (2.80%; 95% CI: 1.86% to 4.21% vs. 3.12%; 95% CI: 1.92% to 5.03%; p = 0.674). Patients with nonparoxysmal AF/AFL had a 4-fold higher LA thrombus prevalence compared with paroxysmal patients (4.81%; 95% CI: 3.35% to 6.86% vs. 1.03%; 95% CI: 0.52% to 2.03%; p < 0.001). LA thrombus prevalence was higher among patients undergoing cardioversion versus ablation (5.55%; 95% CI: 3.15% to 9.58% vs. 1.65%; 95% CI: 1.07% to 2.53%; p < 0.001). Patients with CHA2DS2-VASc scores ≥3 had a higher LA thrombus prevalence compared with patients with scores ≤2 (6.31%; 95% CI: 3.72% to 10.49% vs. 1.06%; 95% CI: 0.45% to 2.49%; p < 0.001). CONCLUSIONS LA thrombus prevalence is high in subgroups of anticoagulated patients with AF/AFL, who may benefit from routine pre-procedural TEE use before cardioversion or catheter ablation.
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Cite This Study
Lurie et al. (2021) conducted a meta-analysis in Atrial fibrillation or atrial flutter (n=14,653). Guideline-directed anticoagulation (VKAs or DOACs) was evaluated on Left atrial (LA) thrombus prevalence (95% CI 1.95-3.80). Among patients with AF/AFL on guideline-directed anticoagulation, the mean-weighted left atrial thrombus prevalence was 2.73% (95% CI 1.95-3.80%), with higher rates in nonparoxysmal AF.