Impact of left atrial appendage flow velocity on thrombus resolution and clinical outcomes in patients with atrial fibrillation and silent left atrial thrombi: insights from the LAT study

Europace. 2024 May 2;26(5):euae120. doi: 10.1093/europace/euae120.

Abstract

Aims: Blood stasis is crucial in developing left atrial (LA) thrombi. LA appendage peak flow velocity (LAAFV) is a quantitative parameter for estimating thromboembolic risk. However, its impact on LA thrombus resolution and clinical outcomes remains unclear.

Methods and results: The LAT study was a multicentre observational study investigating patients with atrial fibrillation (AF) and silent LA thrombi detected by transoesophageal echocardiography (TEE). Among 17 436 TEE procedures for patients with AF, 297 patients (1.7%) had silent LA thrombi. Excluding patients without follow-up examinations, we enrolled 169 whose baseline LAAFV was available. Oral anticoagulation use increased from 85.7% at baseline to 97.0% at the final follow-up (P < 0.001). During 1 year, LA thrombus resolution was confirmed in 130 (76.9%) patients within 76 (34-138) days. Conversely, 26 had residual LA thrombi, 8 had thromboembolisms, and 5 required surgical removal. These patients with failed thrombus resolution had lower baseline LAAFV than those with successful resolution (18.0 [15.8-22.0] vs. 22.2 [17.0-35.0], P = 0.003). Despite limited predictive power (area under the curve, 0.659; P = 0.001), LAAFV ≤ 20.0 cm/s (best cut-off) significantly predicted failed LA thrombus resolution, even after adjusting for potential confounders (odds ratio, 2.72; 95% confidence interval, 1.22-6.09; P = 0.015). The incidence of adverse outcomes including ischaemic stroke/systemic embolism, major bleeding, or all-cause death was significantly higher in patients with reduced LAAFV than in those with preserved LAAFV (28.4% vs. 11.6%, log-rank P = 0.005).

Conclusion: Failed LA thrombus resolution was not rare in patients with AF and silent LA thrombi. Reduced LAAFV was associated with failed LA thrombus resolution and adverse clinical outcomes.

Keywords: Atrial fibrillation; Left atrial appendage flow velocity; Left atrial thrombus; Oral anticoagulant; Transesophageal echocardiography.

Publication types

  • Observational Study
  • Multicenter Study

MeSH terms

  • Aged
  • Aged, 80 and over
  • Anticoagulants* / therapeutic use
  • Asymptomatic Diseases
  • Atrial Appendage* / diagnostic imaging
  • Atrial Appendage* / physiopathology
  • Atrial Fibrillation* / complications
  • Atrial Fibrillation* / physiopathology
  • Atrial Function, Left
  • Blood Flow Velocity
  • Echocardiography, Transesophageal*
  • Female
  • Heart Diseases / complications
  • Heart Diseases / diagnostic imaging
  • Heart Diseases / physiopathology
  • Humans
  • Male
  • Middle Aged
  • Risk Factors
  • Thromboembolism / etiology
  • Thromboembolism / physiopathology
  • Thrombosis* / complications
  • Thrombosis* / diagnostic imaging
  • Thrombosis* / physiopathology
  • Time Factors
  • Treatment Outcome