Usefulness of two-dimensional speckle tracking echocardiography in assessment of left atrial fibrosis degree and its application in atrial fibrillation

Abstract

This study aimed to establish a clinical prediction model for assessing the degree of left atrial fibrosis (LAF) in patients with atrial fibrillation (AF) by combining two-dimensional speckle tracking echocardiography (2D-STE). Additionally, the study sought to evaluate the predictive utility of 2D-STE for left atrial appendage thrombosis (LAAT) and the recurrence of AF after radiofrequency catheter ablation (RFA). A total of 195 patients with AF were included, and late gadolinium enhanced cardiac magnetic resonance was adopted to assess LAF degree. Fibrotic tissue as a percentage of total left atrial wall volume > 20% was defined as severe LAF. Echocardiographic parameters were obtained and analyzed using 2D-STE. The patients were randomly divided into two cohorts (7:3) as the training and testing cohorts. Independent predictors of severe LAF were determined via univariate and multivariate logistic regression, including age, CHA₂DS₂-VA score, left atrial appendage emptying fraction (LAA-EF), peak atrial longitudinal strain (PALS), left atrial stiffness index (LASI), left atrial strain during contraction phase (LASct) and left atrial strain during conduit phase (LAScd). The nomogram was established with the above variables and the area under the curve of the nomogram in testing cohorts was 0.89 (95% CI, 0.80-0.98). As validated by receiver operating characteristic curves, calibration curves and decision curve analysis, the nomogram model demonstrated promising potential for clinical application. Besides, by univariate and multivariate logistic regression analyses, CHA₂DS₂-VA score, uric acid, LAA-EF, left atrial appendage peak blood flow emptying velocity (LAA-PEV) and LASct were found to be independent predictors of LAAT, and left atrial appendage length, E/e' and LASct were found to be independent predictors of post-ablation AF recurrence. 2D-STE can be applied to evaluate LAF degree of AF patients and predict LAAT and AF recurrence.

Keywords: Ablation; Atrial fibrillation; Fibrosis; Left atrial appendage thrombosis; Left atrial strain.

Fig. 1

Measurement of left atrial strain during reservoir, contraction and conduit phase in four-chamber and two-chamber views

Fig. 2

The left atrial three-dimensional model and quantification of left atrial fibrosis. (A) A patient with Utah stage I had 3.84% fibrotic tissue in the total volume of the left atrial wall. (B) A patient with Utah stage IV had 57.64% fibrotic tissue in the total volume of the left atrial wall

Fig. 3

Patient selection flowchart. AF: atrial fibrillation; LGE-CMR: late gadolinium enhanced cardiac magnetic resonance; 2D-STE: two-dimensional speckle tracking echocardiography

Fig. 4

The nomogram prediction model for severe left atrial fibrosis. LAA-EF: left atrial appendage emptying fraction; PALS: peak atrial longitudinal strain; LASI: left atrial stiffness index; LASct: left atrial strain during contraction phase; LAScd: left atrial strain during conduit phase

Fig. 5

(A, B) Receiver operating characteristic curves of the nomogram for severe left atrial fibrosis in the training and validation cohorts. (C, D) Calibration plots of the nomogram for severe left atrial fibrosis in the training and validation cohorts. (E, F) Decision curve analysis of the nomogram for severe left atrial fibrosis in the training and validation cohorts

Fig. 6

(A) Receiver operating characteristic curves for predicting left atrial appendage thrombosis. (B) Receiver operating characteristic curves for predicting atrial fibrillation recurrence after ablation. UA: uric acid; LAA-EF: left atrial appendage emptying fraction; LAA-PEV: left atrial appendage peak blood flow emptying velocity; LASct: left atrial strain during contraction phase; LAA-L: left atrial appendage length; E: early diastolic peak velocity of mitral orifice; e′: average early diastolic peak velocity of mitral annular septal and lateral corners; E/e′: E-to-e′ ratio