The aim: To reveal the connections between gut microbiota metabolites and echocardiography (TTE) atrial fibrillation (AF) characteristics in patients with coronary artery disease (CAD). Materials and methods: 300 patients were divided into 3 groups: the first group(CAD) – 149 patients with CAD but without arrhythmias, the second group (CAD+AF) – 124 patients with CAD and AF paroxysm, and the control group – 27 patients without CAD and arrhythmias. TTE was done by ALOKA SSD-5000. The level of trimethylamine (TMA), trimethylamine-N-oxide (TMAO) of plasma, and fecal short-chain fatty acids (SCFA) levels were determined by gas chromatography with mass electron detection. Results: Isocaproic and isobutyric fecal acids appear in group II in comparison with CG. In group ІІ, patients’ rise of TMA (16.13%), TMAO (57.54%) levels, and decreased ratio (26.16%) in comparison with group I was revealed, P<0.05. In group ІІ patients rise of valeric (1128.43%) and depletion of butyric (78.75%), isovaleric (43.71%), caprylic (99.21%) acids, middle chain fatty acids (95.54%), and the total amount of fecal SCFA (17.09%) in comparison with group I was found, P<0.05. In group ІІ, patients’ rise in left atrium diameter (10.03%), left atrium volume (15.40%), and left atrium volume index (11.48%) in comparison with group I was revealed, P<0.05. The largest amount of correlations was observed between echocardiography indexes and TMA (total number = 11), butyric acid (total number = 10) and TMAO (total number = 9). Left atrium diameter index, which commonly increased in patients with atrial fibrillation, was correlated with TMA (r=0.392), TMAO (r=0.333), butyric acid (r=-0.321), isobutyric acid (r=-0.359) and middle chain fatty acids (r=-0.362), P<0.05. Conclusion: Associations between gut microbiota metabolites and TTE AF characteristics in patients with CAD were based mostly on correlations between left atrium indexes and TMA, TMAO, butyric acid, isobutyric acid, and middle chain fatty acids.