The aim of the study is to evaluate by multidetector computed tomography (MDCT) the prevalence, location and size of LA (left atrial) diverticula and accessory appendages, the prevalence of PVs anatomical variants and LAA (left atrial appendage) shapes in patients with atrial fibrillation (AF) compared to patients in sinus rhythm (SR). Images obtained by MDCT in a group of 100 patients with <1 year paroxysmal or persistent AF prior to radiofrequency catheter ablation and in a group of 100 patients in SR with unconfirmed or insignificant (<50%) coronary arteries stenoses were compared. The prevalence of LA diverticula (22% in AF group, 19% in SR group) and accessory appendages (6% in AF group, 5% in SR group) was not significantly different between the two groups. Similar sizes of LA diverticula and accessory appendages were registered in patients with AF and in SR. The prevalence of a common left venous trunk was significantly higher in patients with AF (30%) compared to patients in SR (18%) (p=0.047) and proved to be an independent predictor for AF (odds ratio (OR) 1.32; 95% confidence interval (CI) 0.93-1.51; p=0.002) at multivariate logistic regression. LAA had a complex shape but no significant differences concerning the prevalence of the 4 major types were registered between the groups. In conclusion, the only parameter associated with AF was the presence of a left common trunk suggesting that it is either a consequence or a predisposing factor for the development of AF.