Prediction of low-voltage areas in the left atrium in patients with non-valvular atrial fibrillation by non-invasive markers

Abstract

Aim. To develop a method for predicting the area of low-voltage area (LVA) in the left atrium (LA), associated with the minimum and maximum expected effectiveness of primary radiofrequency ablation (RFA) in patients with non-valvular atrial fibrillation (AF) using non-invasive predictors.Methods. A longitudinal single-center study included 150 symptomatic non-valvular AF pts aged 20-72 years (median 59.0 [51.0; 64.0]), including 63 women (42%) hospitalized for primary RFA; 119 pts (79.3%) had paroxysmal and 31 (20.7%) - persistent AF. All pts initially underwent general clinical examination, transesophageal and advanced transthoracic echocardiography, estimation of NT-proBNP (pg/ml) and growth differentiation factor 15 (GDF-15, pg/ml) in the blood. Electroanatomical mapping was performed in sinus rhythm before RFA. The area of LVA (<0.5 mV) was calculated as percentage of total LA area. Left ventricular (LV) ejection fraction (LVEF) was >50% in all pts.Results. LVA area varied from 0 to 95.3%, median was 13.7% [5.1; 30.9]. Depending on LVA area, pts were divided into 3 groups: 36 pts (<5%) in gr. 1; 74 pts (5-30%) in gr. 2; 40 pts (>30%) in gr. 3. Increase of LVA area was associated with age, presence, and severity of congestive heart failure (CHF), persistent AF, CHA2DS2 -VASc score ≥3 points, increase of LA volume, LV hypertrophy and increase of NT-proBNP and GDF-15 levels. In univariate analysis, LVA area <5% was associated with NT-proBNP level <125 pg/ml, absence of obesity and CHF, lower LA volume index (<28 ml/ m2). Independent predictors of LVA <5% were: NT-proBNP <125 pg/ml, absence of obesity and LA volume index ≤28 ml/ m2. The model was of good quality, C-statistics was 0.775 (p<0.001). In univariate analysis, LVA area >30 % was associated with age >60 years, NT-proBNP >125 pg/ml, GDF-15 >840 pg/ml, persistent AF, presence of LV hypertrophy, LVEF ≤60%, LA volume index ≥ 32 ml/m2. Independent predictors of LVA >30% were: LA volume index ≥32 ml/m2, GDF-15 >840 pg/ml, and LVEF ≤60%. The model was of good quality, C-statistics was 0.752 (p<0.001).Conclusion. Evaluation of noninvasive parameters, including clinical characteristics, echocardiographic parameters, and blood levels of NT-proBNP and GDF-15, allows prediction of electroanatomical substrate in left atrium in pts with non-valvular AF referred to primary RFA.