The coronary vessel system lying in the LVS region is sunken in the relatively abundant epicardial adipose tissue. The distance from the epicardium to the surface of the left ventricular myocardium is thus significant (up to 10 mm). The thickness of the adipose tissue may vary significantly between individuals and between different regions of the LVS (Figure 2) [38,39]. For example, the amount of epicardial adipose tissue along the arcuate line is significantly smaller than in apical aspects of the LVS (Figure 2). This distance might impact ventricular potential amplitude recorded from the great cardiac vein if the epicardial adipose tissue is sufficiently thick. Moreover, the thick adipose tissue layer may have a pro-arrhythmogenic activity and negatively influence the success rate of electrophysiological procedures performed within the LVS [40–42].