CHARACTERISTICS OF THE LEFT ATRIUM MIOCARDIUM STRUCTURE IN PATIENTS WITH ATRIAL FIBRILLATION AND HEALTHY VOLUNTEERS ACCORDING TO THE DATA OF LATE GADOLINIUM ENHANCEMENT CARDIAC MAGNETIC RESONANCE IMAGING

To develop a method of detection and evaluation of the left atrium structural changes based on magnetic resonance imaging (MRI) with late gadolinium enhancement (LGE), 20 patients with atrial fibrillation (AF) during the sinus rhythm (including 13 men) aged 38 58 years (mean age: 52 years) and 5 healthy volunteers (including 3 men) aged 23 39 years (mean age: 27 years) were examined. After the standard clinical examination, MRI using a 1.5 T scanner and commonly accepted scheme was performed. For assessment of the left atrial (LA) myocardial structure, LGE cardiac MRI was performed using the new high resolution MR sequence with ECG and breath synchronization. The analysis of the images obtained consisted of the LA semi-automatic contouring by two experts with subsequent assessment of intensity of the LA myocardium and the LA blood pool signal carried out using the novel software application (LGE Heart Analyzer). An automatic algorithm of assessment of the LA structure with the use of new parameters, diffuse enhancement ratio (DER) and maximum enhancement ratio (MER), was developed. Both of them reflected the contract agent myocardial accumulation. Both DER and MER in the patients with AF were higher than in the healthy volunteers: 1.1 (1.06 1.25) vs. 0.934 (0.923 0.948), p<0.001, and 2.09±0.5 vs. 1.37±0.03, p=0.006, respectively). DER in patients with AF negatively correlated with the LA ejection fraction (EF) (r=-0.452, p=0.04). The original method of detection of LA fibrosis was developed based on comparison of ER with threshold value, with HV MER used as threshold criterion. The extent of LA fibrosis was more pronounced in the patients with AF than in healthy volunteers (24.6±20.6% and 0.03±0.004%; p<0.001) and correlated with the presence of arterial hypertension (r=0.563, p=0.01). The use of the original algorithm showed that DER, MER, and the extent of fibrosis in the patients with AF were higher than in healthy volunteers; it reflects the LA myocardium structural remodeling in the patients with AF. The contrast agent accumulation in the LA myocardium is related to a decreased LA EF and presence of hypertension. The approach mentioned above allows one to assess the LA myocardium structural changes in AF.

atrial fibrillation, atrial structural remodeling, fibrosis, late gadolinium enhancement magnetic resonance imaging

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